Methods of manufacture of immunocompatible chorionic membrane products

ABSTRACT

Provided herein is a placental product comprising an immunocompatible chorionic membrane. Such placental products can be cryopreserved and contain viable therapeutic cells after thawing. The placental product of the present invention is useful in treating a patient with a tissue injury (e.g. wound or burn) by applying the placental product to the injury. Similar application is useful with ligament and tendon repair and for engraftment procedures such as bone engraftment.

RELATED APPLICATIONS

This application claims priority to:

U.S. Provisional Application Ser. No. 61/338,464 entitled “Selectively Immunodepleted Chorionic Membranes”, filed on Feb. 18, 2010 bearing Docket No. 22924US01,

U.S. Provisional Application Ser. No. 61/338,489 entitled “Selectively Immunodepleted Amniotic Membranes”, filed on Feb. 18, 2010 bearing Docket No. 22925US01, and

U.S. Provisional Application Ser. No. 61/369,562 entitled “Therapeutic Products Comprising Vitalized Placental Dispersions filed on Jul. 30, 2010 bearing Docket No 23498US01, the contents of which are hereby incorporated by reference in their entireties.

This application is being co-filed on Feb. 18, 2011 with, and incorporates by reference, applications entitled:

“Methods of Manufacture of Immunocompatible Chorionic Membrane Products”,

“Immunocompatible Amniotic Membrane Products”,

“Methods of Manufacture of Immunocompatible Amniotic Membrane Products”,

“Therapeutic Products Comprising Vitalized Placental Dispersions”, and

“Methods of Manufacture of Therapeutic Products Comprising Vitalized Placental Dispersions.”

FIELD OF THE INVENTION

The present technology relates to products to facilitate wound healing such as placenta membrane-derived products and biologic skin substitutes. The present technology relates to products to protect injured or damaged tissue, or as a covering to prevent adhesions, to exclude bacteria, to inhibit bacterial activity, or to promote healing or growth of tissue. The field also relates to methods of manufacturing and methods of use of such membrane-derived products.

BACKGROUND OF THE INVENTION

Fresh or decellularized placental membranes have been used topically in surgical applications since at least 1910 when Johns Hopkins Hospital reported the use of placental membrane for dermal applications. Subsequently unseparated amnion and chorion were used as skin substitutes to treat burned or ulcerated surfaces. During the 1950's and 60's Troensegaard-Hansen applied boiled amniotic membranes to chronic leg ulcers.

The human chorionic membrane (CM) is one of the membranes that exists during pregnancy between the developing fetus and mother. It is formed by extraembryonic mesoderm and the two layers of trophoblast and surrounds the embryo and other membranes. The chorionic villi emerge from the chorion, invade the endometrium, and allow transfer of nutrients from maternal blood to fetal blood.

Both fresh and frozen CMs have been used for wound healing therapy. When fresh CM is used, there is increased risk of disease transmission. According to published reports, fresh placental tissue, for example, chorionic tissue exhibits cell viability of 100%, however within 28 days of storage above 0° C. diminished cell viability to 15 to 35%. Freezing over a time of 3 weeks reduced cell viability to 13 to 18%, regardless of the temperature or medium. As the CM is believed to be immunogenic, it has not been used in commercial wound healing products.

Two placental tissue graft products containing living cells, Apligraf and Dermagraft, are currently commercially available. Both Apligraf and Dermagraft comprise ex vivo cultured cells. Neither Apligraf nor Dermagraft comprise stem cells. Furthermore, neither Apligraf nor Dermagraft comprise Insulin-like Growth Factor Binding Protein-1 (IGFBP-1) and adiponectin, which are key factors in the natural wound healing process. In addition, neither Apligraf nor Dermagraft exhibit a protease-to-protease inhibitor ratio favorable for wound healing. As wound healing is a multi-factorial biological process, many factors are needed to properly treat a wound; products having non-native cellular populations are less capable of healing wounds relative to a product having an optimal population of cells representing the native array. It would represent an advance in the art to provide a chorion-derived biologic skin substitute comprising a population of cells representing the native array of factors, including, for example, growth factors and cytokines.

Apligraf is a living, bi-layered skin substitute manufactured using neonatal foreskin keratinocytes and fibroblasts with bovine Type I collagen. As used in this application, Apligraf refers to the product available for commercial sale in November 2009.

Dermagraft is cryopreserved human Fibroblasts derived from newborn foreskin tissue seeded on extracellular matrix. According to its product literature, Dermagraft requires three washing steps before use which limits the practical implementation of Dermagraft as a skin substitute relative to products that require less than three washing steps. As used in this application, Dermagraft refers to the product available for commercial sale in November 2009.

Engineered skin substitutes such as Apligraf and Dermagraft do not provide the best potential for wound healing because they comprise sub-optimal cellular compositions and therefore do not provide proper wound healing. For example, neither Apligraf nor Dermagraft comprises stem cells and, as a result, the ratio between different factors secreted by cells does not enable efficient wound healing. Additionally, some factors that are important for wound healing, including EGF, IGFBP1, and adiponectin are absent from both Apligraf and Dermagraft. Additionally, some factors, including MMPs and TIMPs, are present in proportions that differ greatly from the proportions found in the natural wound healing process; this difference significantly alters, among other things, upstream inflammatory cytokine pathways which in turn allows for sub-optimal micro-environments at the wound site. The present inventors have identified a need for the development of chorionic membrane products that more closely resemble natural tissue.

Paquet-Fifield et al. report that mesenchymal stem cells and fibroblasts are important for wound healing (J Clin Invest, 2009, 119: 2795). No product has yet been described that comprise mesenchymal stem cells and fibroblasts.

Both MMPs and TIMPs are among the factors that are important for wound healing. However, expression of these proteins must be highly regulated and coordinated. Excess of MMPs versus TIMPs is a marker of poor chronic wound healing (Liu et al, Diabetes Care, 2009, 32: 117; Mwaura et al, Eur J Vasc Endovasc Surg, 2006, 31: 306; Trengove et al, Wound Rep Reg, 1999, 7: 442; Vaalamo et al, Hum Pathol, 1999, 30: 795).

α2-macroglobulin is known as a plasma protein that inactivates proteinases from all 4 mechanistic classes: serine proteinases, cysteine proteinases, aspartic proteinases, and metalloproteinases (Borth et al., FASEB J, 1992, 6: 3345; Baker et al., J Cell Sci, 2002, 115:3719). Another important function of this protein is to serve as a reservoir for cytokines and growth factors, examples of which include TGF. PDGF, and FGF (Asplin et al, Blood, 2001, 97: 3450; Huang et al, J Biol Chem, 1988; 263: 1535). In chronic wounds like diabetic ulcers or venous ulcers, the presence of high amount of proteases leads to rapid degradation of growth factors and delays in wound healing. Thus, a placental membrane skin substitute comprising α2-macroglobulin would constitute an advance in the art.

bFGF modulates a variety of cellular processes including angiogenesis, tissue repair, and wound healing (Presta et al., 2005, Reuss et al., 2003, and Su et al., 2008). In wound healing models, bFGF has been shown to increase wound closure and enhance vessel formation at the site of the wound (Greenhalgh et al., 1990).

An in vitro cell migration assay is important for assessing the wound healing potential of a skin substitute. The process of wound healing is highly complex and involves a series of structured events controlled by growth factors (Goldman, Adv Skin Wound Care, 2004, 1:24). These events include increased vascularization, infiltration by inflammatory immune cells, and increases in cell proliferation. The beginning stages of wound healing revolve around the ability of individual cells to polarize towards the wound and migrate into the wounded area in order to close the wound area and rebuild the surrounding tissue. Keratinocytes are the primary cell type of the epithelial layer. Upon proper stimulation, they are implicated in the wound healing process (Pastar et al, 2008 and Bannasch et al., 2000). Specifically, they proliferate and migrate into the wound area to promote healing. An assay capable of evaluating the wound healing potential of skin substitutes by examining the correlation between cell migration and wound healing would represent an advance in the art.

SUMMARY OF THE INVENTION

The present invention provides a pharmaceutically acceptable placental product.

A placental product according to the present invention comprises an immunocompatible chorionic membrane in a cryopreservation medium (optionally cryopreserved) and viable native therapeutic cells and native therapeutic factors.

In some embodiments, the placental product further comprises an amniotic membrane that is selectively devitalized.

There is now provided a placental product that is selectively depleted of substantially all immunogenic cells.

There is now provided a placental product that does not contain ex vivo cultured cells.

There is now provided a placental product that comprises at least one of Epidermal Growth Factor, IGFBP1, and Adiponectin.

Optionally, the therapeutic factors include one or more of IGFBP1, adiponectin, α2-macroglobulin, bFGF, and EGF. Optionally, the therapeutic factors include MMP-9 and TIMP1, wherein the ratio of MMP-9:TIMP1 is from about 7 to about 10. Optionally, the therapeutic factors include IGFBP1, adiponectin, α2-macroglobulin, bFGF, EGF, MMP-9, and TIMP1. Optionally, the therapeutic factors include IGFBP1, adiponectin, α2-macroglobulin, bFGF, MMP-9, and TIMP1, wherein the ratio of MMP-9:TIMP1 is from about 7 to about 10. Optionally, the therapeutic factor is present in a substantial amount in comparison to the equivalent unprocessed human placental membrane. Optionally, each placental product embodiment optionally is devoid of ex-vivo expanded cultured cells.

The present invention also provides a method of manufacturing a placental product comprising: obtaining a placenta, wherein the placenta comprises a chorionic membrane, selectively depleting the placenta of immunogenicity, and cryopreserving the placenta, thereby providing a placental product. According to the present invention, the selective depletion step comprises removing immunogenic cells (e.g. CD14+ macrophages and/or trophoblasts) and/or immunogenic factors (e.g. TNFα). Optionally, the selective depletion step comprises selectively immunodepleting the placenta, whereby the placental product is purified from immunogenic cells and/or immunogenic factors. Optionally, the selective depletion step comprises removing a layer of trophoblasts, for example, by treatment with a digestive enzyme and/or mechanical removal. Optionally, the selective depletion step comprises removing CD14+ macrophages by a cryoprocess wherein the placental product is incubated for a period of time (e.g. about 30-60 mins.) at a temperature above freezing (e.g. at 2-8° C.), and then freezing, whereby CD14+ macrophages are selectively killed relative to therapeutic cells.

The present invention also provides a method of screening a placental product for therapy comprising assaying the placental product for immunogenicity and/or therapeutic value. Optionally, the step of assaying the placental product for immunogenicity comprises a Mixed Lymphocyte Reaction (MLR) and/or Lipopolysaccharide (LPS)-induced Tumor Necrosis Factor (TNF)-a secretion. Optionally, the step of assaying the placental product for therapeutic value comprises assaying the placental product for cell migration induction.

The present invention also provides a method of treating a subject comprising administering a placental product to the subject. Optionally, the step of administering comprises applying the placental product to a wound, for example, topically applying the placental product to a skin wound.

The present inventors have identified a need for the development of chorionic membrane products comprising at least one of IGFBP1, and adiponectin, providing superior wound healing properties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts freezing rates of various freezing methods.

FIG. 2 depicts process cell recovery as a function of cryo volume.

FIG. 3 depicts process cell recovery as a function of refrigeration time.

FIG. 4 shows representative images of the live/dead staining of the epithelial layer of fresh amniotic membrane.

FIG. 5 depicts IL-2sR concentrations of various manufacturing intermediates.

FIG. 6 depicts IL-2sR concentrations of various manufacturing intermediates.

FIG. 7 depicts TNF α concentrations from LPS-induced secretion by placental tissues.

FIG. 8 shows representative images of the live/dead staining of the epithelial layer of fresh amniotic membrane.

FIG. 9 depicts a correlation between IL-2sR release and the number of CD45+ cells.

FIG. 10 depicts a correlation between the amount of CD45+ cells present in amnion-derived cell suspensions and immunogenicity in MLR in vitro.

FIG. 11 depicts expression of EGF (A), IGFBP1 (B), and Adiponectin (C) in amniotic and/or chorionic membranes.

FIG. 12 depicts expression of IFN-2a and TGF-β3 in amniotic membrane homogenates.

FIG. 13 depicts expression of BMP-2, BMP-4, PLAB, PIGF (A), and IGF-1 (B) in amniotic membrane homogenates.

FIG. 14 depicts the ratio of MMPs to TIMPs in various membrane products.

FIG. 15 depicts bFGF levels in amniotic and chorionic membranes (CM).

FIG. 16 depicts representative expression of bFGF in chorionic tissue samples derived from two separate placenta donors.

FIG. 17 depicts a schematic of the cell migration assay.

FIG. 18 depicts the results of cell migration assay of various membrane preparations.

FIG. 19 depicts growth factor and adiponectin expression in protein extracts of various membrane preparations.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the following definitions apply:

“Examplary” (or “e.g.” or “by example”) means a non-limiting example.

“hCMSCs: means human chorionic membrane stromal cells. hCMSCs are generally positive for CD73, CD70, CD90, CD105, and CD166; negative for CD45 and CD34, hCMSCs differentiate to mesodermal lineages (osteogenic, chondrogenic, and adipogenic).

“Selective depletion of immunogenicity” or “selective depletion of immunogenic cells or factors” or “selective depletion” means a placental product that retains live therapeutic cells and/or retains therapeutic efficacy for the treatment of tissue injury yet is free, substantially free, or depleted of at least one of immune cell type (e.g. CD14+ macrophages, trophoblasts, and/or vascular-tissue derived cells) and/or immunogenic factor that are otherwise present in a native placenta or chorionic membrane.

“MSC” means mesenchymal stem cells and include fetal, neonatal, adult, or post-natal. “MSCs” include chorionic MSCs (CMSCs). MSCs generally express one or more of CD73, CD90, CD105, and CD166.

“Native cells” means cells that are native, resident, or endogenous to the placental membrane, i.e. cells that are not exogenously added to the placental membrane.

“Native factors” means placental membrane factors that are native, resident, or endogenous to the placental membrane, i.e. factors that are not exogenously added to the placental membrane.

“Placental products” means the instant placental products disclosed herein.

“Substantially free” means present in only a negligible amount or not present at all. For example, when a cell is abundant at least than about 20% or less than about 10% or less than about 1% of the amount in an unprocessed sample.

“Substantial amount” of an element of the present invention, e.g. native factors, therapeutic factors, or selective depletion, means a value at least about 2% or at least 10% in comparison to an unprocessed, not cryopreserved, fresh membrane sample. A substantial amount can optionally be at least about 50%.

“Therapeutic cells” or “beneficial cells” means stromal cells, MSCs, and/or fibroblasts.

“Therapeutic factors” means placenta- or chorionic membrane-derived factors that promote wound healing. Examples include IGFBP1, adiponectin, α2-macroglobulin, and/or bFGF. Other examples include MMP-9 and TIMP1.

“Stromal cells” refers to a mixed population of cells present (optionally in native proportions) composed of neonatal mesenchymal stem cells and neonatal fibroblasts. Both neonatal mesenchymal stem cells and neonatal fibroblasts are immunoprivileged; neither express surface proteins present on immunogenic cell types.

In some embodiments, the present technology discloses placental products for clinical use, including use in wound healing such as diabetic foot ulcers, venous leg ulcers, and burns. The manufacturing process optionally eliminates essentially all potentially immunogenic cells from the placental membrane while preserving of specific cells that play an important role in wound healing.

In some embodiments, the present technology discloses a placental product that is selectively devitalized. There is now provided a placental product that is selectively depleted of substantially all immunogenic cells. There is now provided a placental product that does not contain ex vivo cultured cells. There is now provided a placental product that comprises at least one of IGFBP1, and adiponectin. There is now provided a placental product that comprises IGFBP1. There is now provided a placental product that comprises adiponectin.

In some embodiments, the present technology discloses a method of cyropreserving a placental product that preserves the viability of specific beneficial cells that are the primary source of factors for the promotion of healing to the wound healing process while selectively depleting immunogenic cells (e.g. killing or rendering non-immunogenic) from the chorionic membranes.

In some embodiments, the present technology discloses a bioassay to test immunogenicity of manufactured placental products.

In some embodiments, the present technology discloses a placental product exhibiting a ratio of MMP:TIMP comparable to that exhibited in vivo. The present inventors have identified a need for the development of placental products exhibiting a ratio of MMP-9 and TIMP1 of about 7-10 to one.

In some embodiments, the present technology discloses a placental product that comprises α2-macroglobulin.

The present inventors have identified a need for the development of placental products that comprise α2-macroglobulin.

There is now provided a placental product that inactivates substantially all serine proteinases, cysteine proteinases, aspartic proteinases, and metalloproteinases present in the chorionic membrane. There is now provided a placental product that inactivates substantially all serine proteinases present in the chorionic membrane. There is now provided a placental product that inactivates substantially all cysteine proteinases present in the chorionic membrane. There is now provided a placental product that inactivates substantially all aspartic proteinases present in the chorionic membrane. There is now provided a placental product that inactivates substantially all metalloproteinases present in the chorionic membrane.

In some embodiments, the present technology discloses a placental product that comprises bFGF, optionally in a substantial amount.

In some embodiments, the present technology discloses a placental product exhibiting a protease-to-protease inhibitor ratio favorable for wound healing, optionally in a substantial amount.

In some embodiments, the present technology discloses a cell migration assay capable of evaluating the wound-healing potential of a placental product.

IGFBP1 and adiponectin are among the factors that are important for wound healing. Evaluation of proteins derived from placental products prepared according to the presently disclosed technology reveal that bFGF is one of the major factors secreted in substantial higher quantities by the chorionic membrane. Additionally, the importance of EGF for wound healing together with high levels of bFGF detected in the presently disclosed chorionic membranes support selection of bFGF as a potency marker for evaluation of membrane products manufactured for clinical use pursuant to the present disclosure.

The present technology discloses a cryopreservation procedure for a placental products that selectively depletes immunogenic cells from the a chorionic membranes and preserves the viability of other beneficial cells (including at least one of mesenchymal stem cells, and fibroblasts in some embodiments and all of mesenchymal stem cells and fibroblasts in some embodiments) that are the primary source of factors for the promotion of healing. During the development of cryopreservation methodology for chorionic membranes, the inventors of the present application evaluated key parameters of cryopreservation including volume of cryopreservative solution, effect of tissue equilibration prior to freezing, and cooling rates for a freezing procedures.

Placental products, their usefulness, and their immunocompatability are surprisingly enhanced by depletion of maternal trophoblast and selective elimination of CD14+ fetal macrophages. Immunocompatability can be demonstrated by any means commonly known by the skilled artisan, such demonstration can be performed by the mixed Lymphocyte Reaction (MLR) and by lipopolysaccharide (LPS)-induced Tumor Necrosis Factor (TNF)-a secretion.

The instant placental products contain bFGF, optionally at a substantial concentration.

The instant placental products optionally secrete factors that stimulate cell migration and/or wound healing. The presence of such factors can be demonstrated by any commonly recognized method. Optionally, the factors are in a substantial amount,

For example, commercially available wound healing assays exist (Cell Biolabs) and cell migration can be assessed by cell line (HMVEC, Lonza Inc.). In one embodiment, conditioned medium from the present placental products enhance cell migration.

The placental products disclosed herein are useful in treating a number of wounds including: tendon repair, cartilage repair (e.g. femoral condyle, tibial plateau), ACL replacement at the tunnel/bone interface, dental tissue augmentation, fistulas (e.g. Crohn's disease, G-tube, tracheoesophogeal), missing tissue at adhesion barriers (e.g. nasal septum repair, vaginal wall repair, abdominal wall repair, tumor resection), dermal wounds (e.g. partial thickness burns, toxic epidermal necrolysis, epidermolysis bullosa, pyoderma gangrenosum, ulcers e.g. diabetic ulcers (e.g. foot), venous leg ulcers), surgical wounds, hernia repair, tendon repair, bladder repair, periosteum replacement, keloids, organ lacerations, epithelial defects, and repair or replacement of a tympanic membrane.

The placental products disclosed herein exhibit one or more of the following properties beneficial to the wound healing process:

-   -   a. approximate number of cells per cm² being about 20,000 to         about 200,000,     -   b. thickness of about 40 to about 400 μm,     -   c. a thin basement membrane,     -   d. low immunogenicity,     -   e. and cryopreserved/cryopreserveable,     -   f. human Chorionic Membrane Stromal Cells (hCMSC),

The present inventors have now identified a need for the development of placental products that do not contain ex vivo cultured cells.

The present inventors have now identified a need for the development of placental products comprising IGFBP1.

The present inventors have now identified a need for the development of placental products comprising adiponectin.

The present inventors have now identified a need for the development of placental products exhibiting a protease-to-protease inhibitor ratio favorable for wound healing.

The present inventors have now identified a need for the development of a method of cyropreserving placental products that preserves the viability of specific cells that are other beneficial cells that are the primary source of factors for the promotion of healing to the wound healing process while selectively depleting immunogenic cells from chorionic membranes.

The present inventors have now identified a need for the development of a bioassay to test immunogenicity of manufactured placental products.

The present inventors have now identified a need for the development of placental products exhibiting a ratio of MMP to TIMP comparable to that exhibited in viva The present inventors have now identified a need for the development of placental products exhibiting a ratio of MMP-9 and TIMP1 of about 7-10 to one.

The present inventors have now identified a need for the development of placental products that comprise α2-macroglobulin.

The present inventors have now identified a need for the development of placental products that inactivate serine proteinases, cysteine proteinases, aspartic proteinases, and metalloproteinases. The present inventors have now identified a need for the development of placental products that inactivate serine proteinases. The present inventors have now identified a need for the development of placental products that inactivate cysteine proteinases. The present inventors have now identified a need for the development of placental products that inactivate aspartic proteinases. The present inventors have now identified a need for the development of placental products that inactivate metalloproteinases.

The present inventors have now identified a need for the development of placental products that comprise bFGF.

The present inventors have now identified a need for the development of a cell migration assay to evaluate the potential of placental membrane products.

The present inventors have now identified a need for the development of a placental product for wound healing that comprises mesenchymal stem cells and fibroblasts.

Placental Product

Overview

One embodiment of the present invention provides a placental product comprising a cryopreservation medium and a chorionic membrane, wherein the chorionic membrane comprises viable therapeutic native cells and native therapeutic factors, and wherein the cryopreservation medium comprises a cryopreserving amount of a cryopreservative. According to this embodiment, the chorionic membrane is substantially free of at least one at least one or 2 or 3 immunogenic cell types such as: trophoblasts, CD14+ macrophages, and vascularized tissue-derived cells.

In one embodiment, the chorionic membrane comprises one or more layers which exhibit the architecture of the native chorionic membrane (e.g. has not been homogenized or treated with collagenase).

In one embodiment, the placental product is suitable for dermal application to a wound.

With the teachings provided herein, the skilled artisan can now produce the present placental products. The present disclosure provides methods of manufacture that produce the technical features of the present placental products. Accordingly, in one embodiment, the placental product is manufactured by steps taught herein. The present placental products are not limited to products manufactured by the methods taught here. For example, products of the present invention could be produced through methods that rely on screening steps; e.g. steps to screen for preparations with the described technical features and superior properties.

The present placental products comprises one or more of the following technical features:

-   -   a. the viable therapeutic native cells are capable of         differentiating into cells of more than one lineage (e.g.         osteogenic, adipogenic and/or chonodrogenic lineages),     -   b. the native therapeutic factors include IGFBP1, optionally         present in a substantial amount,     -   c. the native therapeutic factors include adiponectin,         optionally present in a substantial amount,     -   d. the native therapeutic factors include α2-macroglobulin,         optionally present in a substantial amount,     -   e. the native therapeutic factors include bFGF, optionally         present in a substantial amount,     -   f. the native therapeutic factors include EGF, optionally         present in a substantial amount,     -   g. the native therapeutic factors include MMP-9 and TIMP1,         optionally present in a substantial amount,     -   h. the native therapeutic factors include MMP-9 and TIMP1 in a         ratio of about 7 to about 10,     -   i. the placental product does not comprise ex-vivo cultured         cells,     -   j. the cryopreservative medium is present in an amount of         greater than about 20 ml or greater than about 50 ml,     -   k. the cryopreservative comprises DMSO,     -   l. cryopreservative comprises DMSO in a majority amount,     -   m. the cryopreservation medium further comprises albumin,         optionally wherein the albumin is HSA,     -   n. the cryopreservative comprises DMSO and albumin (e.g. HSA),     -   o. the chorionic membrane comprises about 5,000 to about 240,000         cells/cm2 or about 20,000 to about 60,000 cells/cm2,     -   p. the chorionic membrane comprises 20,000 to about 200,000         cells/cm2, with a cell viability of at least about 70%,     -   q. comprises at least: about 7,400 or about 15,000 or about         23,217, or about 35,000, or about 40,000 or about 47,800 of         stromal cells per cm2 of the chorionic membrane,     -   r. comprises about 5,000 to about 50,000 of stromal cells per         cm2 of the chorionic membrane,     -   s. comprises about 4% to about 46% of viable non-culturally         expanded fibroblasts per cm2 of the placental product,     -   t. comprises stromal cells wherein at least: about 40%, or about         50%, or about 60%, or about 70%, or about 74.3%, or about 83.4         or about 90%, or about 92.5% of the stromal cells are viable         after a freeze-thaw cycle,     -   u. comprises stromal cells wherein about 40% to about 92.5% of         the stromal cells are viable after a freeze-thaw cycle,     -   v. the chorionic membrane has a thickness of about 40 μm to         about 400 μm,     -   w. secretes less than about any of: 420 pg/mL, 350 pg/mL, or 280         pg/mL TNF-a into a tissue culture medium upon placing a 2 cm×2         cm piece of the tissue product in a tissue culture medium and         exposing the tissue product to a bacterial lipopolysaccharide         for about 20 to about 24 hours,     -   x. cryopreservation and thawing, secretes less than about any         of: 420 pg/mL, 350 pg/mL, or 280 pg/mL TNF-α into a tissue         culture medium upon placing a 2 cm×2 cm piece of the tissue         product in a tissue culture medium and exposing the tissue         product to a bacterial lipopolysaccharide for about 20 to about         24 hours,     -   y. after refrigeration, cryopreservation and thawing, secretes         less than about any of: 420 pg/mL, 350 pg/mL, or 280 pg/mL TNF-α         into a tissue culture medium upon placing a 2 cm×2 cm piece of         the tissue product in a tissue culture medium and exposing the         tissue product to a bacterial lipopolysaccharide for about 20 to         about 24 hours,     -   z. the maternal side of the chorionic membrane comprises         fragments of extracellular matrix proteins in a concentration         substantially greater than that of a native, unprocessed         chorion, optionally wherein the chorionic membrane has been         treated with Dispase II or wherein a substantial portion of the         protein fragments comprises terminal leucine or phenylalanine,     -   aa. further comprises an amniotic membrane,     -   bb. further comprises an amniotic membrane, wherein the amniotic         membrane comprises a layer of amniotic epithelial cells,     -   cc. further comprises an amniotic membrane, wherein the amniotic         membrane and the chorionic membrane are associated to one         another in the native configuration,     -   dd. further comprises an amniotic membrane, wherein the amniotic         membrane and the chorionic membrane are not attached to one         another in the native configuration,     -   ee. further comprises an amniotic membrane wherein the chorionic         membrane comprises about 2 to about 4 times more stromal cells         relative to the amniotic membrane,     -   ff. does not comprise an amniotic membrane,     -   gg. the chorionic membrane comprises about 2 to about 4 times         more stromal cells relative to an amniotic membrane of the same         area derived from the same placenta, and     -   hh. is suitable for dermal application to a wound;

Cells

According to the present invention, a placental product comprises native therapeutic cells of the chorionic membrane. The cells comprise one or more of stromal cells, MSCs, and fibroblasts.

In one embodiment, the native therapeutic cells comprise viable stromal cells.

In one embodiment, the native therapeutic cells comprise viable MSCs.

In one embodiment, the native therapeutic cells comprise viable fibroblasts.

In one embodiment, the native therapeutic cells comprise viable MSCs and viable fibroblasts.

In one embodiment, the native therapeutic cells comprise viable MSCs and viable fibroblasts.

In one embodiment, the native therapeutic cells comprise viable stromal cells and viable epithelial cells.

In one embodiment, the therapeutic native cells are viable cells capable of differentiating into cells of more than one lineage (e.g. osteogenic, adipogenic and/or chonodrogenic lineages).

In one embodiment, the chorionic membrane comprises about 10,000 to about 360,000 cells/cm² or about 40,000 to about 90,000 cells/cm².

In one embodiment, the chorionic membrane comprises at least: about 7,400 or about 15,000 or about 23,217, or about 35,000, or about 40,000 or about 47,800 of stromal cells per cm² of the chorionic membrane.

In one embodiment, the chorionic membrane comprises about 5,000 to about 50,000 of stromal cells per cm² of the chorionic membrane.

In one embodiment, the chorionic membrane comprises stromal cells wherein at least: about 40%, or about 50%, or about 60%, or about 70%, or about 74.3%, or about 83.4 or about 90%, or about 92.5% of the stromal cells are viable after a freeze-thaw cycle.

In one embodiment, the chorionic membrane comprises stromal cells wherein about 40% to about 92.5% of the stromal cells are viable after a freeze-thaw cycle.

In one embodiment, the chorionic membrane (of the placental product) comprises fibroblasts in about 50% to about 90% of the total cells.

In one embodiment, the chorionic membrane comprises CD14+ macrophage in an amount of less than about 5% or less than about 1% or less than about 0.5%, optionally as demonstrated by a substantial decrease in LPS stimulation of TNFα release.

In one embodiment, the placental product comprises about 2 to about 4 times more stromal cells relative to an amniotic membrane of the same area derived from the same placenta.

In one embodiment, the placental product further comprises an amniotic membrane, wherein the placental product contains about 2 to about 4 times more stromal cells relative to the amniotic membrane.

In one embodiment, the placental product further comprises an amniotic membrane, wherein the amniotic membrane comprises a layer of amniotic epithelial cells.

In one embodiment, the placental product is substantially free of trophoblasts.

In one embodiment, the placental product is substantially free of functional CD14+ macrophages.

In one embodiment, the placental product is substantially free of vascularized tissue-derived cells.

In one embodiment, the placental product is substantially free of trophoblasts, functional CD14+ macrophages, and vascularized tissue-derived cells. Optionally, the placental product comprises viable stromal cells. Optionally, the placental product comprises viable MSCs. Optionally, the placental product comprises viable fibroblasts. Optionally, the placental product comprises viable MSCs and viable fibroblasts.

In one embodiment, the placental product is substantially free of maternal decidual cells.

In one embodiment, the placental product is substantially free of maternal leukocytes and/or trophoblast cells.

In one embodiment, the chorionic membrane (of the placental product) comprises MSCs in an amount of: about 5% to about 30%, about 5% to about 25%, about 5% to about 20%, about 5% to about 15%, about 3% to about 12%, at least about 5%, at least about 10%, or at least about 15%, relative to the total number of cells in the chorionic membrane. Optionally, at least: about 40%, about 50%, about 60%, or about 70% of the MSCs are viable after a freeze-thaw cycle.

In one embodiment, the chorionic membrane (of the placental product) comprises fibroblasts in an amount of: about 50% to about 95%, about 60% to about 90%, or about 70% to about 85%, relative to the total number of cells in the chorionic membrane. Optionally, at least: about 40%, about 50%, about 60%, or about 70% of the fibroblasts are viable after a freeze-thaw cycle.

In one embodiment, the chorionic membrane (of the placental product) comprises functional macrophages in an amount of less than about any of: 5%, 4%, 3%, 2%, 1%, or 0.1%.

In one embodiment, the chorionic membrane (of the placental product) comprises MSCs and functional macrophages in a ratio of greater than about any of:

In one embodiment, the chorionic membrane comprises fibroblasts and functional macrophages in a ratio of greater than about any of: 14:1, 15:1, 16:1, 17:1, 28:1, 30:1, 35:1, 45:1, or 50:1

In one embodiment, the chorionic membrane (of the placental product) comprises fibroblasts and MSCs in a ratio of: about 9:2 to about 17:3.

In one embodiment, the chorionic membrane (of the placental product) comprises MSCs in an amount of: at least about 1,500 cells/cm², at least about 3,000 cells/cm², about 15,000 to about 9,000 cells/cm², or about 3,000 to about 9,000 cells/cm². Optionally, at least: about 40%, about 50%, about 60%, or about 70% of the MSCs are viable after a freeze-thaw cycle.

In one embodiment, the chorionic membrane (of the placental product) comprises fibroblasts in an amount of: at least about 7,000 cells/cm², at least about 14,000 cells/cm², about 7,000 to about 51,000 cells/cm², or about 14,000 to about 51,000 cells/cm². Optionally, at least: about 40%, about 50%, about 60%, or about 70% of the fibroblasts are viable after a freeze-thaw cycle.

In one embodiment, the chorionic membrane (of the placental product) comprises functional macrophages in an amount of: less than about 3,000 cells/cm², or less than about 1,000 cells/cm².

In one embodiment, the placental product is substantially free of ex-vivo cultured cells.

Placental Factors

According to the present invention, a placental product comprises native therapeutic factors of the chorionic membrane.

In one embodiment, the factors include one or more of: IGFBP1, adiponectin, α2-macroglobulin, bFGF, EGF, MMP-9, and TIMP1. Optionally, the factors are present in amounts/cm² that are substantially similar to that of a native chorionic membrane or layer thereof (e.g. ±10% or 20%).

In one embodiment, the factors include IGFBP1, adiponectin, α2-macroglobulin, bFGF, EGF. MMP-9, and TIMP1. Optionally, the factors are present in ratios that are substantially similar to that of a native chorionic membrane or layer thereof. Optionally, the factors are present in amounts/cm² that are substantially similar to that of a native chorionic membrane or layer thereof (e.g. ±10% or 20%).

In one embodiment, the factors include MMP-9 and TIMP1 in a ratio of about 7 to about 10 (e.g about 7). Optionally, the factors are present in amounts/cm² that are substantially similar to that of a native chorionic membrane or layer thereof (e.g. ±10% or 20%).

In one embodiment, the factors include one or more (e.g. a majority or all) of the factors listed in Table 15. Optionally, the factors are present in ratios that are substantially similar to that of a native chorionic membrane or layer thereof. Optionally, the factors are present in amounts/cm² that are substantially similar to that of a native chorionic membrane or layer thereof (e.g. ±10% or 20%).

In one embodiment, the placental product secretes substantially less TNF-α/cm² than a native, unprocessed chorionic membrane.

In one embodiment, the placental product secretes substantially less TNF-a/cm² than a native placental product upon stimulation by LPS or CT.

In one embodiment, the placental product secretes less than about any of: 420 pg/mL, 350 pg/mL, or 280 pg/mL TNF-α into a tissue culture medium upon placing a 2 cm×2 cm piece of the tissue product in a tissue culture medium and exposing the tissue product to a bacterial lipopolysaccharide for about 20 to about 24 hours.

In one embodiment, after cryopreservation and thawing, the placental product secretes less than about any of: 420 pg/mL, 350 pg/mL, or 280 pg/mL TNF-α into a tissue culture medium upon placing a 2 cm×2 cm piece of the tissue product in a tissue culture medium and exposing the tissue product to a bacterial lipopolysaccharide for about 20 to about 24 hours.

In one embodiment, after refrigeration, cryopreservation and thawing, the placental product secretes less than about any of: 420 pg/mL, 350 pg/mL, or 280 pg/mL TNF-α into a tissue culture medium upon placing a 2 cm×2 cm piece of the tissue product in a tissue culture medium and exposing the tissue product to a bacterial lipopolysaccharide for about 20 to about 24 hours.

In one embodiment, the placental product further comprises an exogenously added inhibitor of TNF-α. Optionally, the inhibitor of TNF-α is IL-10.

In one embodiment, the product has been treated with an antibiotic

Architecture

A placental product of the present invention comprises one or more non-trophoblast layers which exhibit the architecture of the native chorionic membrane. With the teachings provided herein, the skilled artisan will recognize placental layers that exhibit native architecture, for example, layers that have not been homogenized or treated with collagenase or other enzyme that substantially disrupts the layer.

In one embodiment, the placental product comprises a stromal layer with native architecture.

In one embodiment, the placental product comprises a basement membrane with native architecture.

In one embodiment, the placental product comprises a reticular layer with native architecture.

In one embodiment, the placental product comprises a reticular layer and a basement layer with native architecture.

In one embodiment, the placental product comprises a stromal layer, a basement layer, and a reticular layer with native architecture.

In one embodiment, the placental product is substantially free of trophoblasts.

In one embodiment, the placental product comprises a basement membrane with native architecture and the chorionic membrane is substantially free of trophoblasts. Optionally, the maternal side of the placental product comprises fragments of extracellular matrix proteins in a concentration substantially greater than that of a native chorionic membrane. Optionally, the placental product has been treated with Dispase (e.g. Dispase II) and/or a substantial portion of the extracellular matrix protein fragments comprises terminal leucine or phenylalanine.

In one embodiment, the placental product has a thickness of about 40 μm to about 400 μm.

In one embodiment, the placental product further comprises an amniotic membrane. Optionally, the amniotic membrane and the chorionic membrane in the placental product are associated to one another in the native configuration. Alternatively, the amniotic membrane and the chorionic membrane are not attached to one another in the native configuration.

In one embodiment, the placental product does not comprise an amniotic membrane.

Formulation

According to the present invention, the placental product can be formulated with a cryopreservation medium.

In one embodiment, the cryopreservation medium comprising one or more cell-permeating cryopreservatives, one or more non cell-permeating cryopreservatives, or a combination thereof.

Optionally, the cryopreservation medium comprises one or more cell-permeating cryopreservatives selected from DMSO, a glycerol, a glycol, a propylene glycol, an ethylene glycol, or a combination thereof.

Optionally, the cryopreservation medium comprises one or more non cell-permeating cryopreservatives selected from polyvinylpyrrolidone, a hydroxyethyl starch, a polysacharide, a monosaccharides, a sugar alcohol, an alginate, a trehalose, a raffinose, a dextran, or a combination thereof.

Other examples of useful cryopreservatives are described in “Cryopreservation” (BioFiles Volume 5 Number 4—Sigma-Aldrich® datasheet).

In one embodiment, the cryopreservation medium comprises a cell-permeating cryopreservative, wherein the majority of the cell-permeating cryopreservative is DMSO. Optionally, the cryopreservation medium does not comprise a substantial amount of glycerol.

In one embodiment, the cryopreservation medium comprises DMSO. Optionally, the cryopreservation medium does not comprise glycerol in a majority amount. Optionally, the cryopreservation medium does not comprise a substantial amount of glycerol.

In one embodiment, the cryopreservation medium comprises additional components such as albumin (e.g. HSA or BSA), an electrolyte solution (e.g. Plasma-Lyte), or a combination thereof.

In one embodiment, the cryopreservation medium comprises 1% to about 15% albumin by weight and about 5% to about 20% cryopreservative by volume (e.g. about 10%). Optionally, the cryopreservative comprises DMSO (e.g. in a majority amount).

In one embodiment, the placental product is formulated in greater than about 20 ml or greater than about 50 ml of cryopreservation medium. Optionally, the cryopreservative comprises DMSO (e.g. in a majority amount). Optionally, the cryopreservation medium does not comprise a substantial amount of glycerol.

In one embodiment, the placental product is placed on nitrocellulose paper.

In one embodiment, the placenta is cut into a plurality of sections. Optionally, the sections are less than about 10 cm×10 cm. Optionally, the sections are between about 2 cm×2 cm and 5 cm×5 cm.

Manufacture

Overview

A placental product of the present invention can manufactured from a placenta in any suitable manner that provides the technical features taught herein. According to the present invention, a placental product comprises at least an immunocompatible chorionic membrane.

In one embodiment, a placental product is manufactured by a method comprising:

-   -   a. obtaining a placenta,     -   b. selectively depleting the placenta of immunogenicity; and     -   c. cryopreserving the placenta.

In one embodiment, a placental product is manufactured by a method comprising:

-   -   a. obtaining a placenta;     -   b. removing a substantial portion of trophoblasts from the         placenta; and     -   c. cryopreserving the placenta.

Optionally, the method comprises a step of removing the amniotic membrane or portion thereof. Can amniotic membrane') from the placenta. Optionally, the method comprises a step of removing an amniotic membrane from the placenta without removing a substantial portion of amniotic epithelial cells from the placenta.

Optionally, the step of removing a substantial portion of trophoblasts from the placenta comprises treating the placenta with a digestive enzyme such as a protease (e.g. dispase or dispase II), mechanically removing trophoblasts from the placenta (e.g. by scraping), or a combination thereof.

Optionally, the method comprises a step of removing vascularized tissue from the placenta, for example, by lysing red blood cells, by removing blood clots, or a combination thereof.

Optionally, the method comprises a step of treating the placenta with one or more antibiotics.

Optionally, the method comprises a step of selective depletion of CD14+ macrophages.

Optionally, the step of cryopreserving the placenta comprises freezing the placenta in a cryopreservation medium which comprises one or more cell-permeating cryopreservatives, one or more non cell-permeating cryopreservatives, or a combination thereof.

Optionally, the step of cryopreserving the placenta comprises refrigerating for a period of time and then freezing, thereby selectively depleting CD14+ macrophages.

An examplary placental product of the present invention can be manufactured or provided with a bandage or skin substitute.

Immunocompatability and Selective Depletion

In one embodiment, the invention the placental product is immunocompatible. Immunocompatability can be accomplished by any selective depletion step that removes immunogenic cells or factors or immunogenicity from the placenta (or chorionic membrane thereof).

In one embodiment, the placental product is made immunocompatible by selectively depleting it of functional immunogenic cells. A placenta can be made immunocompatible by selectively removing immunogenic cells from the placenta (or chorionic membrane thereof) relative to therapeutic cells. For example, immunogenic cells can be removed by killing the immunogenic cells or by purification of the placenta there from.

In one embodiment, the placenta is made immunocompatible by selectively depleting trophoblasts, for example, by removal of the trophoblast layer.

In one embodiment, the placenta is made immunocompatible by selective depletion of functional CD14+ macrophages, optionally resulting in depletion of TNFα upon stimulation, or a combination thereof.

In one embodiment, the placenta is made immunocompatible by selective depletion of vascularized tissue-derived cells.

In one embodiment, the placenta is made immunocompatible by selective depletion of functional CD14+ macrophages, trophoblasts, and vascularized tissue-derived cells.

In one embodiment, the placenta product is made immunocompatible by selective depletion of trophoblasts and/or CD14+ macrophages, optionally resulting in depletion of TNFα upon stimulation.

Trophoblast Removal

In one embodiment, trophoblasts are depleted or removed from the placental product. Surprisingly, such a placental product has one or more of the following superior features:

-   -   a. is substantially non-immunogenic;     -   b. provides remarkable healing time; and     -   c. provides enhanced therapeutic efficacy.

Trophoblasts can be removed in any suitable manner which substantially diminishes the trophoblast content of the placental product. Optionally, the trophoblasts are selectively removed or otherwise removed without eliminating a substantial portion of one or more therapeutic components from the placenta (e.g. MSCs, placental factors, etc). Optionally, a majority (e.g. substantially all) of the trophoblasts are removed.

One method of removing trophoblasts comprises treating the placenta (e.g. chorion or amino-chorion) with a digestive enzyme such as dispase (e.g. dispase II) and separating the trophoblasts from the placenta. Optionally, the step of separating comprises mechanical separation such as peeling or scraping. Optionally, scraping comprises scraping with a soft instrument such as a finger.

One method of removing trophoblasts comprises treating the chorionic membrane with dispase for about 30 to about 45 minutes separating the trophoblasts from the placenta. Optionally, the dispase is provided in a solution of about less than about 1% (e.g. about 0.5%). Optionally, the step of separating comprises mechanical separation such as peeling or scraping. Optionally, scraping comprises scraping with a soft instrument such as a finger.

Useful methods of removing trophoblasts from a placenta (e.g. chorion) are described by Portmann-Lanz et al. (“Placental mesenchymal stem cells as potential autologous graft for pre- and perinatal neuroregeneration”; American Journal of Obstetrics and Gynecology (2006) 194, 664-73), (“Isolation and characterization of mesenchymal cells from human fetal membranes”; Journal Of Tissue Engineering And Regenerative Medicine 2007; 1: 296-305.), and (Concise Review: Isolation and Characterization of Cells from Human Term Placenta: Outcome of the First International Workshop on Placenta Derived Stem Cells”).

In one embodiment, trophoblasts are removed before cryopreservation.

Macrophage Removal

In one embodiment, functional macrophages are depleted or removed from the placental product. Surprisingly, such a placental product has one or more of the following superior features:

-   -   a. is substantially non-immunogenic;     -   b. provides remarkable healing time; and     -   c. provides enhanced therapeutic efficacy.

Functional macrophages can be removed in any suitable manner which substantially diminishes the macrophage content of the placental product. Optionally, the macrophages are selectively removed or otherwise removed without eliminating a substantial portion of one or more therapeutic components from the placenta (e.g. MSCs, placental factors, etc). Optionally, a majority (e.g. substantially all) of the macrophages are removed.

One method of removing immune cells such as macrophages comprises killing the immune cells by rapid freezing rates such as 60-100° C./min.

Although immune cells can be eliminated by rapid freezing rates, such a method can also be detrimental to therapeutic cells such as stromal cells (e.g. MSCs). The present inventors have discovered a method of selectively killing CD14+ macrophages can be selectively killed by refrigerating the placenta for a period of time (e.g. for at least about 10 min such as for about 30-60 mins) at a temperature above freezing (e.g. incubating at 2-8° C.) and then freezing the placenta (e.g. incubating at −80° C.±5° C.). Optionally, the step of freezing comprises freezing at a rate of less than 10°/min (e.g. less than about 5°/min such as at about 1°/min).

In one embodiment, the step of refrigerating comprises soaking the placenta in a cryopreservation medium (e.g. containing DMSO) for a period of time sufficient to allow the cryopreservation medium to penetrate (e.g. equilibrate with) the placental tissues. Optionally, the step of freezing comprises reducing the temperature at a rate of about 1°/min. Optionally, the step of freezing comprises freezing at a rate of less than 10°/min (e.g. less than about 5°/min such as at about 1°/min).

In one embodiment, the step of refrigerating comprises soaking the placenta in a cryopreservation medium (e.g. containing DMSO) at a temperature of about −10-15° C. (e.g. at 2-8° C.) for at least about any of: 10 min, 20 min, 30 min, 40 min, or 50 min.

In another embodiment, the step of refrigerating comprises soaking the placenta in a cryopreservation medium (e.g. containing DMSO) at a temperature of about −10-15° C. (e.g. at 2-8° C.) for about any of: 10-120, 20-90 min, or 30-60 min. Optionally, the step of freezing comprises freezing at a rate of less than 10°/min (e.g. less than about 5°/min such as at about 1°/min).

Removal of Vascularized Tissue-Derived Cells

In one embodiment, vascularized tissue-derived cells (or vascularized tissue) are depleted or removed from the placental product. Surprisingly, such a placental product has one or more of the following superior features:

-   -   a. is substantially non-immunogenic;     -   b. provides remarkable healing time; and     -   c. provides enhanced therapeutic efficacy.

Vascularized tissue-derived cells can be removed in any suitable manner which substantially diminishes such cell content of the placental product. Optionally, the vascularized tissue-derived cells are selectively removed or otherwise removed without eliminating a substantial portion of one or more therapeutic components from the placenta (e.g. MSCs, placental factors, etc).

In one embodiment, removal of vascularized tissue-derived cells comprises separating the chorion from the placenta by cutting around the placental skirt on the side opposite of the umbilical cord. The chorion on the umbilical side of the placenta is not removed due to the vascularization on this side.

In one embodiment, removal of vascularized tissue-derived cells comprises rinsing the chorionic membrane (e.g. with buffer such as PBS) to remove gross blood clots and any excess blood cells.

In one embodiment, removal of vascularized tissue-derived cells comprises treating the chorionic membrane with an anticoagulant (e.g. citrate dextrose solution).

In one embodiment, removal of vascularized tissue-derived cells comprises separating the chorion from the placenta by cutting around the placental skirt on the side opposite of the umbilical cord and rinsing the chorionic membrane (e.g. with buffer such as PBS) to remove gross blood clots and any excess blood cells.

In one embodiment, removal of vascularized tissue-derived cells comprises separating the chorion from the placenta by cutting around the placental skirt on the side opposite of the umbilical cord and treating the chorionic membrane with an anticoagulant (e.g. citrate dextrose solution).

In one embodiment, removal of vascularized tissue-derived cells comprises separating the chorion from the placenta by cutting around the placental skirt on the side opposite of the umbilical cord, rinsing the chorionic membrane (e.g. with buffer such as PBS) to remove gross blood clots and any excess blood cells, and treating the chorionic membrane with an anticoagulant (e.g. citrate dextrose solution).

Selective Depletion of Immunogenicity as Demonstrated by a Substantial Decrease in LPS Stimulation of TNFα Release.

In one embodiment, the placental product is selectively depleted of immunogenicity as demonstrated by a reduction in LPS stimulated TNF-α release. depletion d of TNF-α depleted or removed from the placental product.

In one embodiment, TNF-α is depleted by killing or removal of macrophages.

In one embodiment, TNF-α is depleted by treatment with an anti-TNF-α antibody.

In one embodiment, TNF-α is functionally depleted by treatment with IL-10, which suppresses TNF-α secretion.

Preservation

A placental product of the present invention may be used fresh or may be preserved for a period of time. Surprisingly, cryopreservation results in immunocompatible placental products.

In one embodiment, a placental product is cryopreserved. A placental product may be cryopreserved by incubation at freezing temperatures (e.g. a −80° C.±5° C.) in a cryopreservative medium.

Cryopreservation can comprise, for example, incubating the placental product at 4° C. for 30-60 min, and then incubating at −80° C. until use. The placental product may then be thawed for use. Optionally, the placental product is cryopreserved in a manner such that cell viability is retained surprisingly well after a freeze-thaw cycle.

In one embodiment, cryopreservation comprises storage in a cryopreservation medium comprising one or more cell-permeating cryopreservatives, one or more non cell-permeating cryopreservatives, or a combination thereof. Optionally, the cryopreservation medium comprises one or more cell-permeating cryopreservatives selected from DMSO, a glycerol, a glycol, a propylene glycol, an ethylene glycol, or a combination thereof. Optionally, the cryopreservation medium comprises one or more non cell-permeating cryopreservatives selected from polyvinylpyrrolidone, a hydroxyethyl starch, a polysacharide, a monosaccharides, a sugar alcohol, an alginate, a trehalose, a raffinose, a dextran, or a combination thereof. Other examples of useful cryopreservatives are described in “Cryopreservation” (BioFiles Volume 5 Number 4—Sigma-Aldrich® datasheet).

In one embodiment, the cryopreservation medium comprises a cell-permeating cryopreservative, wherein the majority of the cell-permeating cryopreservative is DMSO. Optionally, the cryopreservation medium does not comprise a substantial amount of glycerol.

In one embodiment, the cryopreservation medium comprises DMSO. Optionally, the cryopreservation medium does not comprise glycerol in a majority amount. Optionally, the cryopreservation medium does not comprise a substantial amount of glycerol.

In one embodiment, the cryopreservation medium comprises additional components such as albumin (e.g. HSA or BSA), an electrolyte solution (e.g. Plasma-Lyte), or a combination thereof.

In one embodiment, the cryopreservation medium comprises 1% to about 15% albumin by weight and about 5% to about 20% cryopreservative by volume (e.g. about 10%). Optionally, the cryopreservative comprises DMSO (e.g. in a majority amount).

In one embodiment, cryopreservation comprises placing the placenta on nitrocellulose paper.

In one embodiment, the placenta is cut into a plurality of sections before cryopreservation. Optionally, the sections are placed on nitrocellulose paper before refrigeration.

Methods of Use

The placental products (e.g. derived from chorionic tissue) of the present invention may be used to treat any tissue injury. A method of treatment may be provided, for example, by administering to a subject in need thereof, a placental product of the present invention.

A typical administration method of the present invention is topical administration. Administering the present invention can optionally involve administration to an internal tissue where access is gained by a surgical procedure.

Placental products can be administered autologously, allogeneically or xenogeneically.

In one embodiment, a present placental product is administered to a subject to treat a wound. Optionally, the wound is a laceration, scrape, thermal or chemical burn, incision, puncture, or wound caused by a projectile. Optionally, the wound is an epidermal wound, skin wound, chronic wound, acute wound, external wound, internal wounds, congenital wound, ulcer, or pressure ulcer. Such wounds may be accidental or deliberate, e.g., wounds caused during or as an adjunct to a surgical procedure. Optionally, the wound is closed surgically prior to administration.

In one embodiment, a present placental product is administered to a subject to treat a burn. Optionally, the burn is a first-degree burn, second-degree burn (partial thickness burns), third degree burn (full thickness burns), infection of burn wound, infection of excised and unexcised burn wound, loss of epithelium from a previously grafted or healed burn, or burn wound impetigo.

In one embodiment, a present placental product is administered to a subject to treat an ulcer, for example, a diabetic ulcer (e.g. foot ulcer).

In one embodiment, a placental product is administered by placing the placental product directly over the skin of the subject, e.g., on the stratum corneum, on the site of the wound, so that the wound is covered, for example, using an adhesive tape. Additionally or alternatively, the placental product may be administered as an implant, e.g., as a subcutaneous implant.

In one embodiment, a placental product is administered to the epidermis to reduce rhtids or other features of aging skin. Such treatment is also usefully combined with so-called cosmetic surgery (e.g. rhinoplasty, rhytidectomy, etc.).

In one embodiment, a placental product is administered to the epidermis to accelerate healing associated with a dermal ablation procedure or a dermal abrasion procedure (e.g. including laser ablation, thermal ablation, electric ablation, deep dermal ablation, sub-dermal ablation, fractional ablation, and microdermal abrasion).

Other pathologies that may be treated with placental products of the present invention include traumatic wounds (e.g. civilian and military wounds), surgical scars and wounds, spinal fusions, spinal cord injury, avascular necrosis, reconstructive surgeries, ablations, and ischemia.

In one embodiment, a placental product of the present invention is used in a tissue graft procedure. Optionally, the placental product is applied to a portion of the graft which is then attached to a biological substrate (e.g. to promote healing and/or attachment to the substrate). By way of non-limiting example, tissues such as skin, cartilage, ligament, tendon, periosteum, perichondrium, synovium, fascia, mesenter and sinew can be used as tissue graft.

In one embodiment, a placental product is used in a tendon or ligament surgery to promote healing of a tendon or ligament. Optionally, the placental product is applied to portion of a tendon or ligament which is attached to a bone. The surgery can be any tendon or ligament surgery, including, e.g. knee surgery, shoulder, leg surgery, arm surgery, elbow surgery, finger surgery, hand surgery, wrist surgery, toe surgery, foot surgery, ankle surgery, and the like. For example, the placental product can be applied to a tendon or ligament in a grafting or reconstruction procedure to promote fixation of the tendon or ligament to a bone.

Through the insight of the inventors, it has surprisingly been discovered that placental products of the present invention provide superior treatment (e.g. healing time and/or healing strength) for tendon and ligament surgeries. Tendon and ligament surgeries can involve the fixation of the tendon or ligament to bone. Without being bound by theory, the present inventors believe that osteogenic and/or chondrogenic potential of MSCs in the present placental products promotes healing process and healing strength of tendons or ligaments. The present inventors believe that the present placental products provide an alternative or adjunctive treatment to periosteum-based therapies. For example, useful periosteum based treatments are described in Chen et al. (“Enveloping the tendon graft with periosteum to enhance tendon-bone healing in a bone tunnel: A biomechanical and histologic study in rabbits”; Arthroscopy. 2003 March; 19(3):290-6), Chen et al. (“Enveloping of periosteum on the hamstring tendon graft in anterior cruciate ligament reconstruction”; Arthroscopy. 2002 May-June; 18(5):27E), Chang et al. (“Rotator cuff repair with periosteum for enhancing tendon—bone healing: a biomechanical and histological study in rabbits”; Knee Surgery, Sports Traumatology, Arthroscopy Volume 17, Number 12, 1447-1453), each of which are incorporated by reference.

As non-limiting example of a method of tendon or ligament surgery, a tendon is sutured to and/or wrapped or enveloped in a placental membrane and the tendon is attached to a bone. Optionally, the tendon is placed into a bone tunnel before attached to the bone.

In one embodiment, the tendon or ligament surgery is a graft procedure, wherein the placental product is applied to the graft. Optionally, the graft is an allograft, xenograft, or an autologous graft.

In one embodiment, the tendon or ligament surgery is repair of a torn ligament or tendon, wherein the placental product is applied to the torn ligament or tendon.

Non-limiting examples of tendons to which a placental product can be applied include a digitorum extensor tendon, a hamstring tendon, a bicep tendon, an Achilles Tendon, an extensor tendon, and a rotator cuff tendon.

In one embodiment, a placental product of the present invention is used to reduce fibrosis by applying the placental product to a wound site.

In one embodiment, a placental product of the present invention is used as an anti-adhesion wound barrier, wherein the placental product is applied to a wound site, for example, to reduce fibrosis (e.g. postoperative fibrosis).

Non-limiting examples of wound sites to which the placental product can be applied include those that are surgically induced or associated with surgery involving the spine, laminectomy, knee, shoulder, or child birth, trauma related wounds or injuries, cardiovascular procedures, angiogenesis stimulation, brain/neurological procedures, burn and wound care, and ophthalmic procedures. For example, optionally, the wound site is associated with surgery of the spine and the stromal side of the placental product is applied to the dura (e.g. the stromal side facing the dura). Direction for such procedures, including the selection of wound sites and/or methodologies, can be found, for example, in WO 2009/132186 and US 2010/0098743, which are hereby incorporated by reference.

A placental product of the present invention can optionally be used to reduce adhesion or fibrosis of a wound. Postoperative fibrosis is a natural consequence of all surgical wound healing. By example, postoperative peridural adhesion results in tethering, traction, and compression of the thecal sac and nerve roots, which cause a recurrence of hyperesthesia that typically manifests a few months after laminectomy surgery. Repeated surgery for removal of scar tissue is associated with poor outcome and increased risk of injury because of the difficulty of identifying neural structures that are surrounded by scar tissue. Therefore, experimental and clinical studies have primarily focused on preventing the adhesion of scar tissue to the dura matter and nerve roots. Spinal adhesions have been implicated as a major contributing factor in failure of spine surgery. Fibrotic scar tissue can cause compression and tethering of nerve roots, which can be associated with recurrent pain and physical impairment.

Without being bound by theory, the present inventors believe that placental products taught herein are useful to reduce adhesion or fibrosis of a wound, at least in part, because the placental products can perform the very critical function in-situ of providing a immunoprivileged environment (i.e. relatively high resistance against immune responses) in the human development process. One advantage of the wound dressings and processes of the present invention is that an anti-adhesion barrier is provided which can be used to prevent adhesions following surgery, and in particular following back surgery.

In the preceding paragraphs, use of the singular may include the plural except where specifically indicated. As used herein, the words “a,” “an,” and “the” mean “one or more,” unless otherwise specified. In addition, where aspects of the present technology are described with reference to lists of alternatives, the technology includes any individual member or subgroup of the list of alternatives and any combinations of one or more thereof.

The disclosures of all patents and publications, including published patent applications, are hereby incorporated by reference in their entireties to the same extent as if each patent and publication were specifically and individually incorporated by reference.

It is to be understood that the scope of the present technology is not to be limited to the specific embodiments described above. The present technology may be practiced other than as particularly described and still be within the scope of the accompanying claims.

Likewise, the following examples are presented in order to more fully illustrate the present technology. They should in no way be construed, however, as limiting the broad scope of the technology disclosed herein.

The presently described technology and its advantages will be better understood by reference to the following examples. These examples are provided to describe specific embodiments of the present technology. By providing these specific examples, it is not intended limit the scope and spirit of the present technology. It will be understood by those skilled in the art that the full scope of the presently described technology encompasses the subject matter defined by the claims appending this specification, and any alterations, modifications, or equivalents of those claims.

EXAMPLES

Other features and embodiments of the present technology will become apparent from the following examples which are given for illustration of the present technology rather than for limiting its intended scope.

Example 1 Characterization of Placental Membranes

Characterization of cells in placental membranes by Fluorescence Activated Cell Sorting (FACS) demonstrated the presence of stromal cells (Mesenchymal Stem Cell-like cells) in addition to fetal epithelial cells and Fibroblasts in amniotic and/or chorionic membranes.

One unique characteristic of the presently disclosed placental products is the presence of MSCs, which have been shown to be one of three types of cells (in addition to epithelial cells and fibroblasts) that are important for wound healing. Placental membranes secrete a variety of factors involved in wound healing such as angiogenic factors, factors supporting proliferation and migration of epithelial cells and fibroblasts, factors attracting endothelial stem cells from blood circulation to the wound site, antibacterial factors, and others.

Evaluation of proteins secreted by examplary placental products of the invention in comparison to Apligraf and Dermagraft demonstrated a number of growth factors present in the tested products that are involved in wound healing. Examples are Vascular Endothelial Growth Factor (VEGF), Platelet-Derived Growth Factor (PDGF), Transforming Growth Factor (TGF) and others. However, several unique factors including Epidermal Growth Factor (EGF), which is one of the key factors for wound healing, are present in placental membranes and absent in Apligraf and Dermagraft. Also, placental membranes have a favorable protease-to-protease inhibitor ratio for wound healing. In an in vitro model of wound healing (cell migration assay, disclosed herein), the present inventors have demonstrated that placental membranes secrete factors promoting cell migration that will support wound closure.

Example 2 Examplary Manufacturing Process of a Placental Product

In one embodiment, the present application discloses a procedure for manufacturing chorionic membranes from placenta post partum.

Example 2.1 Examplary Manufacturing Process of Chorionic Membrane Product

One method of manufacturing a placental product comprising a chorionic membrane according to the presently disclosed manufacturing procedure is as follows:

-   -   a. Remove umbilical cord close to placental surface,     -   b. Blunt dissect of the amnion to placental skirt,     -   c. Flip placenta over and completely remove amnion,     -   d. Remove chorion by cutting around placental skirt,     -   e. Rinse the chorionic membrane in PBS to remove red blood         cells,     -   f. Rinse the chorionic membrane once with 11% ACD-A solution to         assist in red blood cell removal,     -   g. Rinse the chorionic membrane PBS to remove ACD-A solution,     -   h. Treat chorion in 0.5% dispase solution at 37° C.±2° C. for         30-45 minutes, optionally, during dispase incubation period, use         PBS to remove any remaining blood from the amnion,     -   i. When dispase treatment is complete, rinse chorion with PBS to         remove dispase solution, Gently remove trophoblast layer from         the chorion, for example, by scraping (e.g. with finger),     -   k. Place chorion into a bottle containing antibiotic solution         and incubate at 37° C.±2° C. for 24-28 hrs,     -   l. Remove bottle from the incubator and rinse each membrane with         PBS to remove antibiotic solution,     -   m. Mount chorion on reinforced nitrocellulose paper and cut to         size,     -   n. Place each piece into an FP-90 cryobag and heat seal,     -   o. Add 50 mL cryopreservation solution to the bag through a         syringe and remove any air trapped within the bag with the         syringe,     -   p. Tube seal the solution line on the FP-90 bag,     -   q. Place filled bag into secondary bag and heat seal,     -   r. Place unit into packaging carton,     -   s. Refrigerate at 2-8° C. for 30-60 minutes, Freeze at −80°         C.±5° C. inside a Styrofoam container.

Example 2.2 Examplary Manufacturing Process of Product Comprising Chorionic Membrane and Amniotic Membrane

One method of manufacturing a placental product comprising a chorionic membrane and an amniotic membrane according to the presently disclosed manufacturing procedure is as follows:

-   -   a. Remove umbilical cord close to placental surface,     -   b. Blunt dissect of the amnion to placental skirt,     -   c. Flip placenta over and completely remove amnion,     -   d. Remove chorion by cutting around placental skirt,     -   e. Rinse both membranes in PBS to remove red blood cells,     -   f. Rinse both membranes once with 11% ACD-A solution to assist         in red blood cell removal,     -   g. Rinse both membranes with PBS to remove ACD-A solution,     -   h. Treat chorion in 0.5% dispase solution at 37° C.±2° C. for         30-45 minutes, optionally, during dispase incubation period, use         PBS to remove any remaining blood from the amnion,     -   i. Gently remove the connective tissue layer from the amnion,     -   j. Place the amnion in PBS and set aside,     -   k. When dispase treatment is complete, rinse chorion with PBS to         remove dispase solution,     -   l. Gently remove trophoblast layer from the chorion,     -   m. Place the amnion and chorion each into a bottle containing         antibiotic solution and incubate at 37° C.±2° C. for 24-28 hrs,     -   n. Remove bottles from the incubator and rinse each membrane         with PBS to remove antibiotic solution,     -   o. Mount amnion (epithelial side up) or chorion on reinforced         nitrocellulose paper and cut to size,     -   p. Place each piece into an FP-90 cryobag and heat seal,     -   q. Add 50 mL cryopreservation solution to the bag through a         syringe and remove any air trapped within the bag with the         syringe,     -   r. Tube seal the solution line on the FP-90 bag,     -   s. Place filled bag into secondary bag and heat seal,     -   t. Place unit into packaging carton,     -   u. Refrigerate at 2-8° C. for 30-60 minutes, Freeze at −80°         C.±5° C. inside a Styrofoam container.

Example 2.3 Examplary Placental Product Manufacturing Process

One method manufacturing a placental product comprising a chorionic membrane according to the presently disclosed manufacturing procedure was as follows:

The placenta was processed inside a biological safety cabinet. The umbilical cord was first removed, and the amniotic membrane was peeled from the underlying chorionic membrane using blunt dissection. Subsequently, the chorion was removed by cutting around the placental skirt on the side opposite of the umbilical cord. The chorion on the umbilical side of the placenta was not removed due to the vascularization on this side. The chorionic membrane was rinsed with phosphate buffered saline (PBS) (Gibco Invitrogen, Grand Island, N.Y.) to remove gross blood clots and any excess blood cells. The membrane was then washed with 11% anticoagulant citrate dextrose solution (USP) formula A (ACD-A) (Baxter Healthcare Corp., Deerfield, Ill.) in saline (Baxter Healthcare Corp., Deerfield, Ill.) to remove remaining blood cells.

The chorion was then incubated in 200 mL of a 0.5% dispase (BD Biosciences, Bedford, Mass.) solution in Dulbecco's Modified Eagles media (DMEM) (Lonza, Walkersville, Md.) at 37° C.±2° C. for 30-45 minutes to digest the connective tissue layer between the chorion and adjacent trophoblast layer. Once the chorion incubation period was complete, the chorion was rinsed with PBS to remove the dispase solution. Subsequently, the trophoblast layer was removed by gently peeling or scraping away these maternal decidual cells.

The chorion was then disinfected in 500 mL of antibiotic solution consisting of gentamicin sulfate (50 μg/mL) (Abraxis Pharmaceutical Products, Schaumburg, Ill.), vancomycin HCl (50 μg/mL) (Hospira Inc., Lake Forest, Ill.), and amphotericin B (2.5 μg/mL) (Sigma Aldrich, St. Louis, Mo.) in DMEM at 37° C.±2° C. for 24-28 hours. Vented caps were used with the incubation flasks. After the incubation period, the membrane was washed with PBS to remove any residual antibiotic solution.

The membrane was mounted on Optitran BA-S 85 reinforced nitrocellulose paper (Whatman, Dassel, Germany) and cut to the appropriate size prior to packaging into an FP-90 cryobag (Charter Medical Ltd., Winston-Salem, N.C.). Once the membrane unit was placed into the FP-90 cryobag and the cryobag was heat sealed, 50 mL of a cryopreservation solution containing 10% dimethyl sulfoxide (DMSO) (Bioniche Teo. Inverin Co., Galway, Ireland) and 5% human serum albumin (HSA) (Baxter, West Lake Village, Calif.) in PlasmaLyte-A (Baxter Healthcare Corp., Deerfield, Ill.) were added through the center tubing line. Any excess air was removed, and the tubing line was subsequently sealed.

The FP-90 cryobag was placed into a mangar bag (10 in.×6 in.) (Mangar Industries, New Britain, Pa.), which was then heat sealed. The mangar bag was placed into a packaging carton (10.5 in.×6.5 in.×0.6 in.) (Diamond Packaging, Rochester, N.Y.). All cartons were refrigerated at 2-8° C. for 30-60 minutes prior to freezing at −80° C.±5° C. inside a Styrofoam container.

Example 2.4 Examplary Manufacturing Process of a Placental Product Comprising Chorionic Membrane and Amniotic Membrane

One method of manufacturing a placental product comprising a chorionic membrane product and an amniotic membrane product according to the presently disclosed manufacturing procedure was as follows:

The placenta was processed inside a biological safety cabinet. The umbilical cord was first removed, and the amniotic membrane was peeled from the underlying chorionic membrane using blunt dissection. Subsequently, the chorion was removed by cutting around the placental skirt on the side opposite of the umbilical cord. The chorion on the umbilical side of the placenta was not removed due to the vascularization on this side. Both membranes were rinsed with phosphate buffered saline (PBS) (Gibco Invitrogen, Grand Island, N.Y.) to remove gross blood clots and any excess blood cells. The membranes were then washed with 11% anticoagulant citrate dextrose solution (USP) formula A (ACD-A) (Baxter Healthcare Corp., Deerfield, Ill.) in saline (Baxter Healthcare Corp., Deerfield, Ill.) to remove remaining blood cells.

The chorion was then incubated in 200 mL of a 0.5% dispase (BD Biosciences, Bedford, Mass.) solution in Dulbecco's modified eagles media (DMEM) (Lonza, Walkersville, Md.) at 37° C.±2° C. for 30-45 minutes to digest the connective tissue layer between the chorion and adjacent trophoblast layer. During this incubation period, the stromal side of the amnion was cleaned by gently scraping away any remaining connective tissue. Once the chorion incubation period was complete, the chorion was rinsed with PBS to remove the dispase solution. Subsequently, the trophoblast layer was removed by gently peeling or scraping away these maternal decidual cells.

The amnion and chorion were then each disinfected in 500 mL of antibiotic solution consisting of gentamicin sulfate (50 μg/mL) (Abraxis Pharmaceutical Products, Schaumburg, Ill.), vancomycin HCl (50 μg/mL) (Hospira Inc., Lake Forest, Ill.), and amphotericin B (2.5 μg/mL) (Sigma Aldrich, St. Louis, Mo.) in DMEM at 37° C.±2° C. for 24-28 hours. Vented caps were used with the incubation flasks. After the incubation period, the membranes were washed with PBS to remove any residual antibiotic solution.

The membranes were mounted on Optitran BA-S 85 reinforced nitrocellulose paper (Whatman, Dassel, Germany) and cut to the appropriate size prior to packaging into an FP-90 cryobag (Charter Medical Ltd., Winston-Salem, N.C.). For the amnion, the stromal side was mounted towards the nitrocellulose paper. Once a membrane unit was placed into the FP-90 cryobag and the cryobag was heat sealed, 50 mL of a cryopreservation solution containing 10% dimethyl sulfoxide (DMSO) (Bioniche Teo. Inverin Co., Galway, Ireland) and 5% human serum albumin (HSA) (Baxter, West Lake Village, Calif.) in PlasmaLyte-A (Baxter Healthcare Corp., Deerfield, Ill.) were added through the center tubing line. Any excess air was removed, and the tubing line was subsequently sealed.

The FP-90 cryobag was placed into a mangar bag (10 in.×6 in.) (Mangar Industries, New Britain, Pa.), which was then heat sealed. The mangar bag was placed into a packaging carton (10.5 in.×6.5 in.×0.6 in.) (Diamond Packaging, Rochester, N.Y.). All cartons were refrigerated at 2-8° C. for 30-60 minutes prior to freezing at −80° C.±5° C. inside a Styrofoam container.

Example 3 Quantitative Evaluation of Cell Number and Cell Viability after Enzymatic Digestion of Placental Membranes

Amnion and chorion membranes and present placental products (from above) were evaluated for cell number and cell viability throughout the process. These analyses were performed on fresh placental tissue (prior to the antibiotic treatment step), placental tissue post antibiotic treatment, and product units post thaw. Cells were isolated from the placental membranes using enzymatic digestion. For the frozen product units, the FP-90 cryobags were first removed from the packaging cartons and mangar bags. Then the FP-90 cryobags were thawed for 2-3 minutes in a room temperature water bath. Early experiments involved the use of a 37° C.±2° C. water bath. After thaw, the placental membranes were removed from the FP-90 cryobag and placed into a reservoir containing saline (Baxter Healthcare Corp., Deerfield, Ill.) for a minimum of 1 minute and a maximum of 60 minutes. Each membrane was detached from the reinforced nitrocellulose paper prior to digestion.

Amniotic membranes were digested with 40 mL of 0.75% collagenase (Worthington Biochemical Corp., Lakewood, N.J.) solution at 37° C.±2° C. for 20-40 minutes on a rocker. After collagenase digestion, the samples were centrifuged at 2000 rpm for 10 minutes. The supernatant was removed, and 40 mL of 0.05% trypsin-EDTA (Lonza, Walkersville, Md.) were added and incubated at 37° C.±2° C. for an additional 5-15 minutes on a rocker. The trypsin was warmed to 37° C.±2° C. in a water bath prior to use. After trypsin digestion, the suspension was filtered through a 100 μm cell strainer nylon filter to remove any debris. Centrifugation at 2000 rpm for 10 minutes was performed, and supernatant was removed. Cell pellets were reconstituted with a volume of PlasmaLyte-A that was proportional to the pellet size, and 20 μL of the resuspended cell suspension were mixed with 80 μL of trypan blue (Sigma Aldrich, St. Louis, Mo.) for counting. The cell count sample was placed into a hemocytometer and evaluated using a microscope.

Chorionic membranes were digested with 25 mL of 0.75% collagenase solution at 37° C.±2° C. for 20-40 minutes on a rocker. After collagenase digestion, the suspension was filtered through a 100 μm cell strainer nylon filter to remove any debris. Centrifugation at 2000 rpm for 10 minutes was performed, and supernatant was removed. Cell pellets were reconstituted with a volume of PlasmaLyte-A that was proportional to the pellet size, and 20 μL of the resuspended cell suspension were mixed with 80 μL of trypan blue for counting. The cell count sample was placed into a hemocytometer and evaluated using a microscope.

Placenta membranes were analyzed prior to any processing to determine the initial characteristics of the membranes. Table 1 contains the average cell count per cm² and cell viability values for the amniotic and chorionic membranes from 32 placenta lots.

The average cell count per cm² for the amniotic membrane was 91,381 cells with a corresponding average cell viability of 84.5%. For the chorionic membrane, the average cell count per cm² was 51,614 cells with a corresponding cell viability of 86.0%.

As certain methods of manufacture are taught herein to retain chorionic membrane cells, these data further demonstrate that the present methods can produce placental products that comprise a chorionic membrane containing about 20,000 to about 200,000 cells/cm².

Since the amniotic membrane consists of epithelial cells and stromal cells, experiments were conducted to determine the ratio of epithelial cells to stromal cells. Amniotic membranes from 3 placenta lots were analyzed. First, a 5 cm×5 cm piece of amniotic membrane was digested with approximately 25 mL of 0.05% Trypsin-EDTA (Lonza, Walkersville, Md.) at 37° C.±2° C. in a water bath for 30 minutes. After the incubation step, epithelial cells were removed by gently scraping the cells from the membrane. After rinsing with PBS (Gibco Invitrogen, Grand Island, N.Y.), the membrane was subsequently digested in the same manner as chorionic membrane (described above). In addition, another intact 5 cm×5 cm piece of amniotic membrane was digested using the standard procedure (described above) to determine the total number of cells. The percentage of stromal cells was then determined by dividing the cell count from the amniotic membrane with the epithelial cells removed with the cell count from the intact membrane.

Results indicate that 19% of the total cells were stromal cells. Therefore, approximately 17,362 stromal cells were present in amniotic membrane with approximately 74,019 epithelial cells. These data indicated that there are approximately 3 times more stromal cells in chorionic membranes as compared to amniotic membranes. As certain methods of manufacture are taught herein to retain stromal cells, this ratio demonstrates that the present methods can produce placental products that comprise a chorionic membrane and amniotic membrane, wherein the chorionic membrane comprises about 2 to about 4 times more stromal cells relative to the amniotic membrane.

TABLE 1 Cell count per cm² and cell viability values from fresh placental tissue from 32 donors. Membrane Statistics Cell Count per cm² Cell Viability Amnion Average 91,381 84.5% SD 49,597 3.7% Chorion Average 51,614 86.0% SD 25,478 4.7%

The second point in the manufacturing process where cell count and cell viability values were assessed was after the antibiotic treatment step. Table 2 provides the results from these analyses. Cell recoveries from this step for the amniotic membrane and the chorionic membrane were 87.7% and 70.3%, respectively.

TABLE 2 Cell count per cm², cell viability, and process (antibiotic treatment) cell recovery values for post antibiotic placental tissue from 28 donors. Cell Count per Process Cell Membrane Statistics cm² Cell Viability Recovery Amnion Average 75,230 84.4% 87.7% SD 46,890 4.2% 49.4% Chorion Average 33,028 85.6% 70.3% SD 18,595 4.4% 31.1%

Example 4 Development of a Placental Product Cryopreservation Procedure

Cryopreservation is a method that provides a source of tissues and living cells. A main objective of cryopreservation is to minimize damage to biological materials during low temperature freezing and storage. Although general cryopreservation rules are applicable to all cells, tissues, and organs, optimization of the cryopreservation procedure is required for each type of biological material. The present application discloses a cryopreservation procedure for placental membrane products that can selectively deplete immunogenic cells from the placental membranes; and preserve viability of other beneficial cells that are the primary source of factors for the promotion of healing.

During cryopreservation method development for placental membranes, the present inventors evaluated key parameters of cryopreservation including volume of cryopreservative solution, effect of tissue equilibration prior to freezing, and cooling rates for a freezing procedures.

Acceptance of tissue allografts in the absence of immunosuppression will depend on the number of satellite immune cells present in the tissue. Cryopreservation is an approach which can be utilized to reduce tissue immunogenicity. This approach is based on differential susceptibility of different cell types to freezing injury in the presence of DMSO; leukocytes are sensitive to fast cooling rates. The freezing rate of 1° C./min is considered optimal for cells and tissues including immune cells. Rapid freezing rates such as 60-100° C./min eliminate immune cells. However, this type of procedure is harmful to other tissue cells, which are desirable for preservation according to the present invention. The developed cryopreservation procedure utilized a cryopreservation medium containing 10% DMSO, which is a key component protecting cells from destruction when water forms crystals at low temperatures. The second step of cryopreservation was full equilibration of placental membrane in the cryopreservation medium, which was achieved by soaking membranes in the cryopreservation medium for 30-60 min at 4° C. This step allowed DMSO to penetrate the placental tissues. Although there are data in the literature showing that tissue equilibration prior to freezing affects survival of immune cells (Taylor & Bank, Cryobiology, 1988, 25:1), it was an unexpected finding that 30-60 min placental membrane equilibration in a DMSO-containing solution at 2-8° C. selectively increases sensitivity of immune cells to freezing (in comparison to therapeutic cells) so that these type of cells are selectively depleted during the freezing process (e.g. 1° C./min freezing rate).

For example, CD14+ macrophages are selectively killed relative to therapeutic cells such as hMSCs and/or fibroblasts.

Temperature mapping experiments were performed to analyze the temperature profiles of potential cryopreservation conditions for the membrane products. These results are illustrated in FIG. 1. Eight (8) FP-90 cryobags were filled with either 20 mL or 50 mL of cryopreservation solution, and temperature probes were placed inside each cryobag. The first set of parameters (conditions 1 through 4 of FIG. 1 a through FIG. 1 d, respectively) involved a 30-minute refrigeration (2-8° C.) step prior to freezing (−80° C.±5° C.). In addition, the analysis involved freezing of the cryobags either inside a Styrofoam container or on the freezer shelf. The second set of parameters (conditions 5 through 8 of FIG. 1 e through FIG. 1 h, respectively) involved direct freezing (−80° C.±5° C.) of the cryobags either inside a Styrofoam container or on the freezer shelf. The results indicated that condition 6 and condition 2 exhibited the most gradual temperature decreases. Gradual temperature decreases are typically desired in order to preserve cell viability. The difference between condition 6 and condition 2 was that condition 2 included a 30-minute refrigeration step. Therefore, the decrease in temperature from the start of freezing to −4° C., where latent heat evolution upon freezing occurs, was examined further. For condition 6, the rate of cooling was approximately −1° C./minute during this period. The rate of cooling for condition 2 was approximately −0.4° C./minute during the same timeframe. Therefore, condition 2 was selected for incorporation into a non-limiting cryopreservation process since slower rates of cooling are generally desired to maintain optimal cell viability.

FIG. 2 depicts the effects of cryopreservation solution volume on process (cryopreservation) cell recovery for the chorionic membrane. The analysis of the 10 mL cryopreservation solution volume involved 5 placenta lots, and the analysis of the 20 mL cryopreservation solution volume included 3 lots. For the 50 mL cryopreservation solution volume, 16 placenta lots were analyzed.

As depicted in FIG. 2, the 50 mL volume of cryopreservation solution volume provided superior cell recovery compared to that of the 10 ml and 20 ml. Since the 50 mL cryopreservation solution volume provided the slowest cooling rate. FIG. 2 indicates that a cooling rate of less than about 2° C./minute or less than about 1° C./minute can provide a superior method of manufacture according to the present invention.

Experiments were conducted to evaluate different potential freezing conditions to maximize cell recovery after the cryopreservation process.

FIG. 3 includes these results, depicting the effects of refrigeration time and freezing parameters on process (cryopreservation) cell recovery for the chorionic membrane. Three conditions were analyzed. These conditions were also linked to the temperature mapping studies. The first condition involved directly freezing the product unit on a shelf within the freezer (−80° C.±5° C.). The second condition also contained a direct freeze, but the product unit was placed into a Styrofoam container within the freezer. The third condition included a refrigeration (2-8° C.) period of 30 minutes prior to the freezing step. For the amniotic membrane, 3 placenta lots were evaluated. Two (2) placenta lots were analyzed for the chorionic membrane. Results indicated that the third condition was optimal for both membrane types. As depicted in

FIG. 3, a refrigeration period at least about 30 min provided the best cell recovery.

Cryopreservation parameters are assessed for the amniotic and chorionic membranes and summarized in Table 3 and Table 4. The evaluation of the cell recoveries and cell viabilities from these experiments resulted in the selection of the final parameters for the manufacturing process. In addition, all average cell viability values were 70%.

TABLE 3 Post thaw cell count per cm², cell viability, and process (cryopreservation) cell recovery values for the chorionic membrane. Process Condition Cell Count Cell Cell Parameter Tested Statistics per cm² Viability Recovery Refrigerate All Average 23,217 87.3% 102.8% at 2-8° C. for conditions SD 9,155  4.1%  65.5% 30-60 min N 27 27 27 and freeze at −80° C. ± 5° C. Dispase 30 min Average 22,354 85.7%  81.1% No decrease treatment SD 9,505  5.1%  32.4% in process cell N 24 24 24 recovery for 45 min Average 27,125 90.6% 172.6% the 45 min SD 7,963  2.2% 101.2% treatment. A N 6  6  6 30-45 min range was established. Refrigeration 30 min Average 23,815 86.8% 102.2% The process time interval SD 9,681  5.2%  68.8% recovery value N 25 25 25 was >80% for 60 min Average 20,773 85.8%  84.9% the 60 min SD 7,356  4.7%  14.4% time interval. N 5  5  5 A 30-60 min range was established. Thawing 37° C. ± Average 33,360 85.9% 114.7% No significant temperature 2° C. water SD 8,497  4.0%  38.1% difference bath N 5  5  5 found in Room Average 21,298 86.8%  96.3% process cell temp SD 8,189  5.3%  67.2% recovery. The water bath N 25 25 25 room temp condition was selected for logistical reasons. Holding 1-15 min Average 23,733 86.6% 100.6% No significant period after SD 9,674  5.1%  67.0% difference transfer into N 26 26 26 found in saline 1 hr Average 20,550 87.0%  91.4% process cell SD 6,575  4.8%  32.0% recovery. N 4  4 4 Membranes can be held in saline for up to 1 hr. Tissue size 5 cm × 5 cm Average 23,391 86.1%  99.6% No decrease SD 8,865  5.0%  58.7% in process cell N 23 23 23 recovery from 2 cm × 2 cm Average 23,036 88.4% 98.7% the 5 cm × 5 SD 11,362  5.0% 81.3% cm product to N 7  7  7 the 2 cm × 2 cm product. Both sizes were acceptable for use. Notes: cm = centimeter; min = minutes; temp = temperature; hr = hour, SD = standard deviation; N = number

TABLE 4 Post thaw cell count per cm², cell viability, and process (cryopreservation) cell recovery values for the amniotic membrane Process Condition Cell Count Cell Cell Comments/ Parameter Tested Statistics per cm² Viability Recovery Conclusions Refrigerate All Average 55,709 83.4% 64.2% Overall at 2-8° C. for conditions SD 45,210  4.4% 22.5% assessment 30-60 min N 32 32 32 and freeze at −80° C. ± 10° C. Refrigeration 30 min Average 52,173 83.1% 63.7% No significant time interval SD 39,750  4.5% 21.4% difference N 26 26 26 found in 60 min Average 71,033 85.0% 66.5% process cell SD 66,525  3.9% 29.3% recovery. A N 6  6  6 30-60 min range was established. Thawing 37° C. ± Average 48,524 83.3% 64.0% No significant temperature 2° C. water SD 27,804  1.7% 34.4% difference bath N 7  7  7 found in Room temp Average 57,721 83.5% 64.3% process cell water bath SD 49,271  4.9% 19.0% recovery. The N 25 25 25 room temp condition was selected for logistical reasons. Holding 1-15 min Average 50,873 83.1% 65.0% No significant period after SD 38,969  3.9% 24.2% difference transfer into N 26 26 26 found in saline 1 hr Average 76,667 85.1% 61.0% process cell SD 66,565  6.2% 14.3% recovery. N 6  6  6 Membranes can be held in saline for up to 1 hr. Tissue size 5 cm × 5 cm Average 58,431 83.3% 62.8% No decrease SD 47,603  4.5% 21.7% in process cell N 28 28 28 recovery from 2 cm × 2 cm Average 36,656 84.4% 73.9% the 5 cm × 5 SD 13,175  3.4% 29.5% cm product to N 4  4  4 the 2 cm × 2 cm product. Both sizes were acceptable for use.

These data indicate that a step of dispase treatment for about 30-45 minutes provides a superior method of manufacture according to the present invention. These data also indicate that a step of refrigeration at 2-8° C. for 30-60 min before freezing provides a superior method of manufacture according to the present invention.

Example 5 Qualitative Evaluation of Cell Viability by Tissue Staining

The amniotic and chorionic membranes were stained using a LIVE/DEAD® Viability/Cytotoxicity kit (Molecular Probes Inc., Eugene, Oreg.) to qualitatively assess cell viability. Staining was performed as per the manufacturer's protocol. Membrane segments of approximately 0.5 cm×0.5 cm were used. Evaluation of stained membranes was performed using a fluorescent microscope. An intense uniform green fluorescence indicated the presence of live cells, and a bright red fluorescence indicated the presence of dead cells. Images of fresh amniotic and chorionic membranes as well as cryopreserved amniotic and chorionic membranes demonstrated that the manufacturing process did not alter the phenotypic characteristics of the membranes and the proportion of viable cell types (epithelial and stromal cells) in the membranes post thaw.

FIG. 4 shows representative images of the live/dead staining of the epithelial layer of fresh amniotic membrane (A); epithelial layer of cryopreserved amniotic membrane (B); stromal layer of fresh amniotic membrane (C); stromal layer of cryopreserved amniotic membrane (D); fresh chorionic membrane (E); and cryopreserved chorionic membrane (F). Live cells are green, and dead cells are red.

Example 6 Placental Tissue Immunogenicity Testing

One unique feature of the human chorion is the absence of fetal blood vessels that prevent mobilization of leukocytes from fetal circulation. On the fetal side, macrophages resident in the chorioamniotic mesodermal layer represent the only population of immune cells. Thus, fetal macrophages present in the chorion are a major source of tissue immunogenicity, as such the chorion is considered immunogenic. In a study where the amnion was used together with the chorion for plastic repair of conjunctival defects, the success rate was low (De Roth Arch Ophthalmol, 1940, 23: 522). Without being bound by theory, the present inventors believe that removal of CD14+ cells from placental membranes eliminates activation of lymphocytes in vitro. In addition to the presence of fetal macrophages, the present inventors believe that immunogenicity of chorion can be mediated by contamination of blood cells coming from the maternal trophoblast, which contains blood vessels. Thus, the processing of placental membrane for clinical use can be enhanced by purification of the chorion from maternal trophoblasts and selective elimination of all CD14+ fetal macrophages. Immunogenicity testing can be used to characterize a chorion-derived product as safe clinical therapeutics. For example, two bioassays can be used to test immunogenicity of manufactured placental products: Mixed Lymphocyte Reaction (MLR) and Lipopolysaccharide (LPS)-induced Tumor Necrosis Factor (TNF)-α secretion.

Example 7 Mixed Lymphocyte Reaction (MLR)

An MLR is a widely used in vitro assay to test cell and tissue immunogenicity. The assay is based on the ability of immune cells (responders) derived from one individual to recognize allogeneic Human Leukocyte Antigen (HLA) and other antigenic molecules expressed on the surface of allogeneic cells and tissues (stimulators) derived from another individual when mixed together in a well of an experimental tissue culture plate. The response of immune cells to stimulation by allogeneic cells and tissues can be measured using a variety of methods such as secretion of particular cytokines (e.g., Interleukin (IL-2), expression of certain receptors (e.g., IL-2R), or cell proliferation, all of which are characteristics of activated immune cells.

Placental tissue samples representing different steps of the presently disclosed manufacturing process were used for immunogenicity testing. These samples included amnion with chorion and trophoblast as a starting material and separated choriotrophoblast, chorion, trophoblast, and amnion. Both freshly purified and cryopreserved (final products) tissues were tested.

For the MLR assay, cells from placental tissues were isolated using 280 U/mL of collagenase type II (Worthington, Cat No. 4202). Tissues were treated with enzyme for 60-90 min at 37° C.±2° C., and the resulting cell suspension was filtered through a 100 μm filter to remove tissue debris. Single cell suspensions were then centrifuged using a Beckman, TJ-6 at 2000 rpm for 10 min and washed twice with DPBS. Supernatant was discarded after each wash, and cells were resuspended in 2 mL of DMEM (Invitrogen, Cat No. 11885) and evaluated for cell number and cell viability by counting cells in the presence of Trypan blue dye (Invitrogen, Cat No. 15250-061). For the MLR, placental-derived cells were mixed with allogeneic hPBMCs at a 1:5 ratio in 24-well culture plates in DMEM supplemented with 5% fetal bovine serum (FBS) and incubated for 4 days in the incubator containing 5% CO₂, 95% humidity at 37° C.±2° C. Human Peripheral Blood Mononuclear Cells (hPBMCs) alone were used as a negative control, and a mixture of two sets of hPBMCs derived from two different donors was used as a positive MLR control. After 4 days of incubation, cells were collected from wells, lysed using a lysis buffer (Sigma, Cat No. C2978) supplemented with protease inhibitor cocktail (Roche, Cat No. 11836153001), and IL-213 was measured in cell lysates using the sIL-2R ELISA kit (R&D Systems, Cat No. SR2A00) generally following the manufacturer's protocol. The level of IL-2R is a measure of activation of T-cells in response to immunogenic molecules expressed by allogeneic cells. Results of 2 out of 12 representative experiments are shown in FIG. 5 and FIG. 6. Results presented in these figures demonstrated that the present application discloses a process for manufacturing of placental membranes that result in low immunogenicity of the final chorionic membrane products.

As depicted in FIG. 5, the manufacturing process serially reduces immunogenicity of the placental product. Samples representing different steps of the manufacturing process Chorion+Trophoblast (CT), Trophoblast (T), Amnion (AM), and Chorion (CM) were co-cultured with hPBMCs for 4 days. IL-2sR was measured in cell lysates as a marker of T-cell activation. Negative control shows a basal level of immune cell activation: PBMCs derived from one donor were cultured alone. Positive control: a mixture of PBMCs derived from 2 different donors.

As depicted in FIG. 6, selective depletion of immunogenicity results from the present cryopreservation process of producing the present placental products, as evidenced by the significant decrease in immunogenicity upon cryopreservation.

Example 8 LPS-Induced TNF-α Secretion by Placental Membrane Cells

As described herein, fetal macrophages present in the amnion and chorion are a major source of tissue immunogenicity. Without being bound by theory, the present inventors believe that removal of CD14+ cells from placental membrane eliminates activation of lymphocytes and that depletion of allogeneic donor tissue macrophages decreases the level of inflammatory cytokine secretion and tissue immunogenicity. The inventors also believe that reduction of tissue immunogenicity can also be reached by depletion of TNF-α with anti-TNF-α antibodies or suppression of TNF-α secretion by IL-10. Macrophages in fetal placental membranes respond to bacteria by secretion of inflammatory cytokines. The secretion of TNF-α by fresh placental membranes in vitro in response to bacterial LPS is significantly higher in the chorionic membrane. Thus, the present inventors believe that immunogenicity of placental membranes is mediated by macrophages, the amount and/or activity of which is higher in the chorionic membrane.

According to the present invention, selective depletion of macrophages is an optional approach to selectively deplete immunogenicity of the amniotic and chorionic membranes, allowing the use of both allogeneic membranes for clinical applications. The assay of functional macrophages in a placental product is used here as an assay for immunogenicity testing (e.g. in production or prior to clinical use) based on the facts that: macrophages are the source of immunogenicity in chorionic membranes. Macrophages in placenta-derived membranes respond to bacterial LPS by secretion of high levels of TNF-α; and TNF-α is a critical cytokine involved in immune response and allograft tissue rejection. Therefore, secretion of TNF-α by placenta-derived membranes in response to LPS is used here to characterize tissue immunogenicity and for pre-use screening.

Example 9 Establishment of Allowed LPS-Induced TNF-α Secretion Level by Chorionic Membranes

Data from published reports regarding the level of TNF-α, which is associated with the absence or an insignificant immune response in a variety of experimental systems, are presented in Table 5. These data indicate that a TNF-α level below 100 pg/mL correlates with a low immune response. The ability of amniotic and chorionic membranes to produce TNF-α spontaneously and in response to bacteria or bacterial LPS in vitro has been shown by a number of investigators. Table 6 summarizes such data. The lowest spontaneous TNF-α secretion by amniotic membrane of about 70 pg/cm² of the membrane was reported by Fortunato et al. (Am J Reprod Immunol, 1994, 32:184). All reports also showed that fresh placental membranes secrete large amounts of TNF-α in response to bacteria or bacterial LPS (Table 6), which is attributed to the presence of viable functional macrophages.

TABLE 5 TNF-α levels associated with the Description of absence/reduction experimental system of immune response Comments References IL-10-induced inhibition Mean 260 pg/mL Wang et al., of MLR in vitro. Transplantation, TNF was measured in 2002, 74: 772 tissue culture supernatant by ELISA. MLR using skin tissue Mean 100 pg/mL explants (0.02 cm² per well) as stimulators in the presence or absence of IL-10 (skin explant assay). Skin tissue destruction was assessed microscopically, and severity was assigned based on histopathological tissue damage. Endogeneous TNF ~0.04 U/mL for the TNF activity Shalaby et al., J production in MLR in the negative control and per mg is not Immunol, 1988, presence or absence of MLR in the presence provided. 141: 499 anti-TNF antibodies. TNF of anti-TNF levels were assessed antibodies, which using the WEHI-164 correlated with no or cytotoxicity assay. significant inhibition of lymphocyte proliferation TNF levels in BAL fluid of Isograft: below Unmodified Sekine et al., J lung isografts, unmodified detection; allograft: ~45 pg/mL Immunol, 1997, allograft, and alveolar AM-depleted allograft: (immunogenic) 159: 4084 macrophages (AM) ~15 pg/mL of BAL depleted allograft in rats. (total 75 pg/5 ml of BAL) TNF levels in MLR after ~<200 pg/mL TNF Ohashi et al, 48 hours in the presence correlated with a Clin Immunol, or absence of advanced complete inhibition of 2010, 134: 345 glycation end products MLR (MLR inhibitors). TNF levels in MLR. <100 pg/mL TNF in Toungouz et al., MLR with HLA- Hum Immunol, matched donors 1993, 38: 221 (control, no stimulation) TNF activity in MLR when Negative control ~20 Unit of activity Lomas et al., pieces of cryopreserved U of TNF activity; was calculated Cell Tissue skin allografts (~0.2 cm²) MLR with skin as TNF in Bank, 2004, were incubated with explants: 0-40 U; ng/mL divided 5: 23. hPBMCs for 24 hours. Positive control: 600 U by OD at 570 nm Positive control: for the hPBMC + LPS; negative: same hPBMC alone. experimental well Cytokine time course in Optimal TNF Jordan & Ritter, MLR, including TNF. after 24 hours: J Immunol ~150 pg/mL Meth, 2002, 260: 1 MLR using skin tissue For no skin Recalculation Dickinson et al., explants (0.02 cm² per destruction: 0.5-1.1 pg/mL per 1 cm² of Cytokine, 1994, well) as stimulators in the for HLA skin tissue: 6: 141 presence or absence of compatible lowest TNF anti-TNF antibodies (skin responders, and 2.6-1376 pg/mL non- explant assay). Skin for immunogenic tissue destruction was unmatched MLR level is 100 pg/cm² assessed microscopically, and severity was assigned based on histopathological tissue damage.

TABLE 6 TNF levels Comments/ secreted by fresh recalculations placental of the lowest Description of membranes in TNF levels per experimental system culture cm² References TNF secretion by Chorion: basal Lowest TNF Zaga et al., Biol “fresh” amnion and 3.3 ± 0.46 ng/cm², level for amnion Reprod, 2004, chorion tissues (1.44 cm²) LPS-induced: 150-250 ng/cm² is 1200 pg/cm² 71: 1296 incubated for 24 Amnion: basal hours in the presence 2.5 ± 1.3 ng/cm², or absence of LPS LPS-induced: ~50 ng/cm² (500 ng/mL). TNF secretion by Basal ~1-2.5 pg/μg Lowest TNF Zaga-Clavellina “fresh” amnion and total protein in the level for amnion et al., Reprod chorion tissues (1.8 cm medium for both is 800 pg/cm² Biol Endocrinol, diameter disks: 2.5 cm²) amnion and 2007, 5: 46 incubated for 24 chorion; hours in the presence E. Coli-induced: or absence of E. Coli amnion → 29.2 in 1 mL medium. (14.5-35.3) pg and chorion → 53.15 (40-94.2) pg per μg total protein TNF secretion by Basal: ~2-64 U/mL 1 unit = ~100-200 pg/mL; Paradowska et “fresh” amnion and or 8-10 mg chorion; Lowest TNF al., Placenta, chorion tissues <1 U/mL for 5-7 mg level for amnion 1997, 18: 441 (chorion 8-10 mg amnion; is <100 pg/mL tissue/mL; amnion 5-7 mg/mL, LPS-induced: >100 corresponding to 0.02-0.04 cm²) U/10 mg for chorion <2500 pg/cm² incubated for 20 hours and ~15-17 U/10 mg in the presence or for amnion absence of LPS (5 μg/mL). TNF secretion by Amnion: Basal → Lowest TNF Fortunato et al., “fresh” amnion (0.57 cm²) 40 pg/mL, level for fresh Am J Obstet in 0.8 mL LPS-induced → amnion is ~70 pg/cm² Gynecol, 1996, incubated for 24 hours 410 pg/mL 174: 1855 in the presence or absence of LPS (50 ng/mL). TNF secretion by Basal: Amnion ~7-13 ng/mL/g Amnion is 5-7 mg Thiex et al., “fresh” amnion and tissue); corresponds Reprod Biol chorion tissues (4 cm²) Chorion ~18 ng/mL/g ~0.02-0.04 cm²; Endocrinol, incubated for 24 tissue 1 g is ~6 cm²; 2009, 7: 117 hours in the presence LPS-induced (1000 ng/mL): Lowest TNF or absence of LPS (1-1000 ng/mL) Amnion level for amnion ~14 ng/mL/g), is ~1000 pg/cm² Chorion ~27 ng/mL/g

Example 10 LPS-Induced TNF-α Secretion Immunogenicity Assay

2 cm×2 cm pieces of placental derived membranes representing production intermediates and final placental products were placed in tissue culture medium and exposed to bacterial LPS (1 μg/mL) for 20-24 hr. After 24 hours, tissue culture supernatant were collected and tested for the presence of TNF-α using a TNF-α ELISA kit (R&D Systems) according to the manufacturer's protocol. Human hPBMCs (SeraCare) known to contain monocytes responding to LPG by secretion of high levels of TNF-α were used as a positive control in the assay. hPBMCs and placental tissues without LPS were also included as controls in the analysis. In this assay, TNF detected in the culture medium from greater than 70 pg/cm² (corresponding to 280 pg/mL) for both spontaneous and LPS-induced TNF-α secretion was considered immunogenic.

The low levels of TNF-α and the absence of the response to DPS by AM and CM indicates the absence of viable functional macrophages that are the major source of immunogenicity for amniotic and chorionic membranes. Results of this assay showed a correlation with the MLR data: tissues that produce high levels of TNF-α in response to LPS are immunogenic in the MLR assay (FIG. 7A and FIG. 7B for TNF-α secretion; FIG. 9, C-MLR).

As depicted in FIG. 7A and FIG. 7B, the manufacturing process serially reduces immunogenicity of the placental product. Samples representing different steps of the manufacturing process (Amnion+Chorion+Trophoblast (ACT), Chorion+Trophoblast (CT), Amnion (AM), and Chorion (CM)) were incubated in the presence of LPS for 24 hr, and after that tissue culture supernatants were tested for the TNF-α by ELISA. Tissues cultured in medium without LPS show the basal level of TNF a secretion. PBMCs, which are known to secrete high levels of TNF, were used as a positive control.

Choriotrophoblast (CT), which secreted high levels of TNF-α (FIG. 7 B), was tested in MLR against two different PBMC donors. CT cells were co-cultured with PBMCs for 4 days. IL-2αR was measured in cell lysates as a marker of T-cell activation. Positive control: a mixture of PBMCs derived from 2 different donors.

FIG. 7C shows that preparations producing high levels of TNF-α are immunogenic. Choriotrophoblast (CT), which secreted high levels of TNF-α (FIG. 7, B), was tested in MLR against two different PBMC donors. CT cells were co-cultured with PBMCs for 4 days. IL-2αR was measured in cell lysates as a marker of T-cell activation. Positive control: a mixture of PBMCs derived from 2 different donors.

Example 11 Analysis of Placental Cells by FACS

Knowing the cellular composition of chorionic membranes is important for developing a thorough understanding of potential functional roles in wound healing and immunogenicity. Previous reports demonstrated that the chorion contains multiple cell types. In addition to fibroblasts, stromal cells were identified in the chorion. Although there are no fetal blood vessels within the chorionic membranes, it comprises resident fetal macrophages. The close proximity to maternal blood circulation and decidua provide a potential source of immunogenic cells (maternal leukocytes and trophoblast cells) and therefore are a potential source of immunogenicity. To investigate the cellular composition of the chorion, FACS analysis was performed.

Example 11.1 FACS Procedure: Single Cell Suspension Preparation

Purified chorionic membranes were used for cellular phenotypic analysis via FACS. Cells from chorion were isolated using 280 U/mL collagenase type II (Worthington, Cat No. 4202). Tissues were treated with enzyme for 60-90 min at 37° C.±2° C., and the resulting cell suspension was filtered through a 100 μm filter to remove tissue debris. Single cell suspensions were then centrifuged using a Beckman TJ-6 at 2000 rpm for 10 min and washed twice with DPBS. Supernatant was discarded after each wash, and cells were resuspended in 2 mL of FACS staining buffer (DPBS+0.09% NaN₃+1% FBS).

Example 11.2 Immunolabeling Cells for Specific Cellular Markers

Once the single cell suspension was prepared according to Example 10.1, a minimum of 1×10⁵ cells in 100 μL of FACS staining buffer was treated with antibodies labeled with fluorescent dye. Table 7 provides descriptions of the antibodies and the amounts used. For cell surface markers, cells were incubated for 30 min at room temperature in the dark with antibodies followed by washing twice with FACS staining buffer by centrifugation at 1300 rpm for 5 min using a Beckman TJ-6 centrifuge. Cells were then resuspended in 400 μL of FACS staining buffer and analyzed using a BD FACSCalibur flow cytometer. To assess cell viability, 10 μL of 7-AAD regent (BD, Cat No. 559925) was added just after the initial FACS analysis and analyzed again. For intracellular staining, cells were permeabilized and labeled following the manufacturer's recommendations (BD Cytofix/Cytoperm, Cat No. 554714) and analyzed using a BD FACSCalibur flow cytometer.

TABLE 7 Description of reagents used for placental cell characterization by FACS. Volume of Cell marker antibody antibody and solution Cell marker Cell marker label type Cat No. used type specificity IgG1 BD 559320  5 μL Cell surface Isotype control isotype-PE CD105-PE Caltag 20 μL Cell surface MSC marker MHCD10504 CD166-PE BD 559263 80 μL Cell surface MSC marker CD45-PE BD 555483 10 μL Cell surface Hematopoietic cell marker IgG2a BD 555574  2 μL Cell surface Isotype control isotype-PE CD14-PE BD 555398 20 μL Cell surface Monocyte marker HLA-DR-PE BD 556644 20 μL Cell surface HLA class II specific for antigen- presenting cells IgG1 BD555748  5 μL Cell surface Isotype control isotype- FITC CD86-FITC BD 557343 20 μL Cell surface Immune co- stimulatory marker CD40-FITC BD 556624 20 μL Cell surface Immune co- stimulatory marker IgG1 Dako X0931 10 μL Intracellular Isotype control isotype- unlabeled Cytokeratin Dako M7018  2 μL Intracellular Trophoblast 7-unlabeled marker Rabbit anti- Dako F0261  5 μL Intracellular Secondary mouse FITC antibody

Example 12 Phenotypic Analysis of Placental Cells

FACS analysis of single cell suspensions of chorionic membranes demonstrates that both membranes contain cells expressing markers specific for mesenchymal stem cells (refer to Table 8), implicating the presence of stromal cells. In addition, several immunogenic markers, which are more likely expressed on CD14+ placental macrophages, were detected. The % ranges for different markers are wide. It can be explained by: 1) high variability in cell number between placenta donors; and 2) technical issues, which include the presence of the high and variable cellular and tissue debris in the cellular suspension. Although debris can be gated out, debris particles that are comparable with cells by size will affect the accuracy of the calculated % for each tested marker. In addition, Table 9 provides a FACS analysis of cells from the chorionic membranes that were cultured in 10% FBS in DMEM at 37° C.±2° C. until confluency (passage 0 cells). These data demonstrated that cells derived from chorionic membranes retained a phenotype similar to MSCs after culturing. In conclusion, the presence of stromal cells in placental tissues was confirmed by FACS analysis.

As certain methods of manufacture are taught herein to retain chorionic membrane cells, these data indicate that the present methods can produce placental products that comprise a chorionic membrane containing MSC-like cells that express CD105, CD166, C90, and/or CD73 (also referred to herein as CMSCs or MSCs).

TABLE 8 Characterization of the cellular composition of placental membranes based on selective CD markers. Marker Chorion (% range) MSC Markers CD105 6.4-78.5 CD166 4.8-51.5 Hematopoietic Cell CD14 0.9-6.1  Markers CD45 4.6-14.7 Immune co-stimulatory HLA-DR   0-14.7 markers CD86 4.9-22.5 CD40  2-5.8 Trophoblast marker Cytokeratin-7 2.71-23.07

TABLE 9 FACS analysis of cultured cells (passage 0) from placenta lot D16. Cell Surface Marker Chorion (%) CD45 0.53 CD166 82.62 CD105 86.73 CD49a 92.26 CD73 94.57 CD41a −0.05 CD34 −0.25 HLA-DR −0.19 CD19 −0.22 CD14 −0.27 CD90 98.00

Example 13 Differentiation Capacity of Cells Derived from the Chorionic Membrane

Therapeutic cells, in optional embodiments of the present invention, are adherent, express specific cellular markers such as CD105 and lack expression of other markers such as CD45, and demonstrate the ability to differentiate into adipocytes, osteoblasts, and chondroblasts.

The expression of specific cellular markers has already been described in Example 12. To determine if the cells within the placental product derived from the chorionic membrane can adhere to plastic and differentiate into one of the lineages, cells were isolated from the placental product derived from the chorion as described in this invention and cultured at 37° C.±2° C. and expanded.

FIG. 8-A shows a representative image of passage 2 cells, demonstrating the ability of the cells to adhere to tissue culture plastic. As a comparison, a representative image of MSCs isolated and expanded from human bone marrow aspirate is shown in FIG. 8-B.

Osteogenic differentiation capacity was demonstrated by staining the cultured cells with alkaline phosphatase labeling following the manufacturer's recommendations (BCIP/NBT Alkaline Phosphatase Substrate Kit IV, Vector Laboratories Cat. No. SK-5400). Alkaline phosphatase is an enzyme involved in bone mineralization (Allori et al., Tissue Engineering Part B, 2008, 8:275), and its expression within cells is indicative of osteo-precursor cells (Majors et al., J Orthopaedic Res, 1997, 15:546). Staining for alkaline phosphatase is carried out through an enzymatic reaction with Bromo-4-Chloro-3′-Indolylphosphate p-Toluidine Salt (BCIP) and Nitro-Blue Tetrazolium Chloride (NTP). BCIP is hydrolyzed by alkaline phosphatase to form an intermediate that undergoes dimerization to produce an indigo dye. The NBT is reduced to the NBT-formazan by the two reducing equivalents generated by the dimerization. Together these reactions produce an intense, insoluble black-purple precipitate when reacted with alkaline phosphatase. FIG. 8-C shows a representative image of passage 2 cells staining positively for alkaline phosphatase.

Example 14 Live CD45+FACS Analysis

As CD45 is a general marker for hematopoietic cells and therefore a marker for the presence immunogenic cells, the presence of CD45+ cells may correlate well with how immunogenic a tissue may be. An initial study indeed showed a correlation between amount of immunogenicity as measured via an in vitro MLR assay of placental tissue at various stages within the manufacturing process (as described previously), and the amount of CD45+ cells was determined via FACS analysis. As FIG. 9 demonstrates, membranes that trigger the expression of high levels of IL-2sR on hPBMC responders in MLR also contained a high percentage of CD45+ cells, indicating that immunogenicity of placental membranes can be correlated with the number of CD45+ cells. Further studies revealed, however, that quantifying CD45+ cells via FACS alone showed high variability that did not allow for the establishment of a safety threshold for CD45+ cells in placental membranes. Accordingly, the inventors evaluated whether or not viability of CD45+ cells is correlated with immunogenicity.

To eliminate some of the variability in CD45+ measurements via FACS, viability of CD45+ cells was assessed, as dead CD45+ cells do not contribute to immunogenicity. To ensure an accurate assessment of live CD45+ cells, a pilot experiment was conducted in which a single cell suspension of amnion membrane was spiked in with a known concentration of live CD45+ cells (hPBMCs) ranging from a theoretical 1.25% to 20% (0.75-12%-actual % of the spiked cells) of the total cell concentration in suspension. Cells were stained with CD45-PE antibody at determined concentrations (refer to Table 10), incubated with 7-AAD cell viability test reagent, and analyzed using a BD FACS Calibur. Table 10 demonstrates that recovery of known amounts of CD45+ cells was not correct (4th column in the table). For example, although 12% of PBMCs was spiked into a single-cell suspension of amnion membrane, only 4.26% of CD45+ cells were recovered according to FACS analysis (>60% difference from the actual spike). To correlate with immunogenicity, MLR was also performed in parallel. Briefly, single cell suspensions of amniotic membrane spiked with various amounts of live hPBMCs were co-cultured with another donor of PBMCs in the MLR. FIG. 10 depicts a correlation between the amount of CD45+ cells present in amnion-derived cell suspensions and immunogenicity in MLR in vitro. Table 10 and FIG. 10 show that the suspensions spiked with higher amounts of live CD45+ cells resulted in higher immunogenicity as measured by IL-2sR expression on the hPBMC responder donor.

TABLE 10 % CD45+ recovery experiments. Cell suspension Sample immunogenicity Description % CD45+ Actual spike (tested in MLR (in % of cell cells (%, based on 60% % Difference and expressed types in the (detected by CD45+ cells in this from actual as IL-2R in mixture) FACS) hPBMC batch) spike pg/mL) 100% amnion 0.65 N/A N/A 20.23 0% PBMC N/A N/A N/A 15.6 (negative control) 100% PBMC 61.51  N/A N/A 86.31 (positive control) 20% PBMC + 4.26 12 64.5% 24.38 80% Amnion 10% PBMC + 2.24 6 62.7% 21.17 90% Amnion 5% PBMC + 1.7  3 43.3% 16.75 95% Amnion 2.5% PBMC + 1.36 1.5 Not 15.9 97.5% calculated* Amnion 1.25% PBMC + 1.06 0.75 Not 12.27 98.75% calculated* Amnion Notes: N/A—not applicable; *Not calculated - values are close to the method detection limits.

Example 15 Protein Array Analyses

The protein profiles of amniotic and chorionic membranes were investigated using a SearchLight Multiplex chemiluminescence array. The presence of proteins in tissue membrane extracts and secreted by tissues in culture medium was investigated. For comparison, two commercially available products containing living cells, Apligraf and Dermagraft, were assayed.

Example 15.1 Dermagraft

Dermagraft membrane was thawed and washed according to the manufacturer's instructions. Dermagraft membrane was cut into 7.5 cm² pieces. For tissue lysates, one 7.5 cm² piece of membrane was snap frozen in liquid nitrogen followed by pulverization using a mortar and pestle. Crushed tissue was transferred to a 1.5 mL microcentrifuge tube and 500 μL of Lysis buffer (Cell Signaling Technologies, Cat No. 9803) with protease inhibitor (Roche, Cat No. 11836153001) was added and incubated on ice for 30 min with frequent vortexing. The sample was then centrifuged at 16000 g for 10 min. The supernatant was collected and sent for protein array analysis by Aushon Biosystems. For tissue culture, one 7.5 cm² piece of membrane was plated onto a well of a 12-well dish and 2 mL of DMEM+1% HSA+ antibiotic/antimycotic were added and incubated at 37° C.±2° C. for 3, 7, or 14 days. After incubation, tissue and culture media were transferred to a 15 mL conical tube and centrifuged at 2000 rpm for 5 min. Culture supernatant was collected and sent for protein array analysis by Aushon Biosystems.

Example 15.2 Apligraf

Apligraf membrane was cut into 7.3 cm² pieces. For tissue lysates, one 7.3 cm² piece of membrane was snap frozen in liquid nitrogen followed by pulverization using a mortar and pestle. Crushed tissue was transferred to a 1.5 mL microcentrifuge tube and 500 μL of Lysis buffer (Cell Signaling Technologies, Cat No. 9803) with protease inhibitor (Roche, Cat No. 11836153001) was added and incubated on ice for 30 min with frequent vortexing. The sample was then centrifuged at 16000 g for 10 min. The supernatant was collected and sent for protein array analysis by Aushon Biosystems. For tissue culture, one 7.3 cm2 piece of membrane was plated onto a well of a 12-well dish and 2 mL of DMEM+1% HSA+ antibiotidantimycotic were added and incubated at 37° C.±2° C. for 3, 7, or 14 days. After incubation, tissue and culture media were transferred to a 15 mL conical tube and centrifuged at 2000 rpm for 5 min. Culture supernatant was collected and sent for protein array analysis by Aushon Biosystems.

Example 15.3 Chorionic Membranes

Chorionic membranes were isolated and packaged at −80° C.±5° C. according to the manufacturing protocols disclosed herein in Example 2. Packaged membranes were then thawed in a 37° C.±2° C. water bath and washed 3 times with DPBS. Membranes were cut into 8 cm² pieces. For tissue lysates, one 8 cm² piece of membrane was snap frozen in liquid nitrogen followed by pulverization using a mortar and pestle. Crushed tissue was transferred to a 1.5 mL microcentrifuge tube and 500 μL of Lysis buffer (Cell Signaling Technologies, Cat No. 9803) with protease inhibitor (Roche, Cat No. 11836153001) was added and incubated on ice for 30 min with frequent vortexing. Tissue lysate was then centrifuged at 16000 g for 10 min. The supernatant was collected and sent for protein array analysis by Aushon Biosystems. For tissue culture, one 8 cm² piece of membrane was plated onto a well of a 12-well dish and 2 mL of DMEM+1% HSA+antibiotic/antimycotic were added and incubated at 37° C.±2° C. for 3, 7, or 14 days. After incubation, tissue and culture media were transferred to a 15 mL conical tube and centrifuged at 2000 rpm for 5 min. Culture supernatant was collected and sent for protein array analysis by Aushon Biosystems.

Initial testing consisted of an analysis of 36 proteins that are important for wound healing. The list of identified proteins is described in Table 11.

TABLE 11 List of selected proteins for analysis. Protein Group Based on Functionality Comments Metalloproteases Matrix Metalloproteinase 1 Matrix and growth factor (MMP1), MMP2,3,7,8,9,10,13 degradation; facilitate cell migration. MMP Inhibitors Tissue Inhibitors of MMPs Have angiogenic activity; (TIMP1 and 2) can be placed in the “angiogenic factors” group. Angiogenic Factors Angiotensin-2 (Ang-2); basic Majority of these factors Fibroblast Growth Factor also have growth and (bFGF); heparin-bound migration stimulatory Epidermal Growth Factor activities and can be (HB-EGF); EGF; FGF-7 (also placed in a group of known as Keratinocyte growth factors. Growth Factor-KGF); Platelet derived Growth Factors (PDGF) AA, AB, and BB; Vascular Endothelial Growth Factor (VEGF), VEGF-C and VEGF-D; Neutrophil gelatinase-associated lipocalin (NGAL); Hepatocyte Growth Factor (HGF); Placenta Growth Factor (PIGF); Pigment Epithelium Derived Factor (PEGF); Thrombopoetin (TPO) Protease Inhibitor/Protein Alpha-2-macroglobulin Inhibit protease activity; Carrier regulate growth factor activity. Growth Factors See “angiogenic factors” + See “angiogenic factors.” Transforming Growth Factor alpha (TGF-a) Cytokines Adiponectin (Acrp-30) Affect keratinocyte functions. Granulocyte Colony- Protection from infections. Stimulating Factor (G-CSF) Interleukin1 Receptor Regulate activity of Antagonist (IL-1RA) inflammatory cytokine IL- 1. Leukemia Inhibitory Factor Support angiogenic (LIF) growth factors. Chemokines SDF-1beta Attracts endothelial and other stem cells from circulation to wound site. Regulators of IGF Insulin-like growth factor Regulate IGF activity. binding protein (IGFBP1,2,3)

Example 15.4 Protein Expression in Present Placental Products

Preliminary protein array data analyses showed that the majority of selected testing factors (see Table 11) were expressed in amniotic membrane, chorionic membrane, Apligraf, and Dermagraft.

Three proteins were identified as unique for the chorionic membrane which are undetectable in Apligraf and Dermagraft. These proteins are EGF. IGFBP1, and Adiponectin). FIG. 11 depicts expression of EGF (A), IGFBP1 (B), and Adiponectin (C) in amniotic or chorionic membranes. CM75 and CM 78 are placental products of the present invention (e.g. cryopreserved), AM75 and AM78 are cryopreserved amniotic membrane products. These proteins are believed by the inventors to facilitate the therapeutic efficacy of the present placental products for wound healing.

These data indicate that the present methods can produce placental products that comprise a chorionic membrane containing EGF, IGFBP1, and/or adiponectin.

Example 16 Wound Healing Proteins are Secreted for a Minimum of 14 Days

Placental products of the present invention demonstrate a durable effect, desirable for wound healing treatments. The extracellular matrix and presence of viable cells within the amniotic membrane described in this invention allow for a cocktail of proteins that are known to be important for wound healing to be present for at least 14 days. Amniotic membranes were thawed and plated onto tissue culture wells and incubated at 37° C.±2° C. for 3, 7, and 14 days. At each time point, a sample of the culture supernatant was collected and measured through protein array analysis as described in Example 15. Table 12 illustrates the level of various secreted factors in tissue culture supernatants from two donors of chorionic membranes at 3, 7 and 14 days as measured through protein array analysis.

TABLE 12 Levels of proteins secreted in chorion tissue culture supernatants at different time points (pg/ml). Day 3 Day 7 hACRP30 298.4 614.3 hAlpha2Macroglobulin 34,480.5 6,952.5 hANG2 0.0 2.0 hEGF 0.7 0.4 hFGF 84.3 13.5 hFibronectin 37,510.9 41,871.4 hHBEGF 102.6 40.0 hHGF 1,382.9 1,715.4 hIGFBP1 201.6 201.0 hIGFBP2 62.7 172.9 hIGFBP3 778.1 812.4 hIL1ra 30,037.4 556.1 hKGF 4.2 2.4 hMMP1 32,388.5 67,665.6 hMMP10 4,016.4 4,140.1 hMMP13 13.3 0.0 hMMP2 768.8 1,230.5 hMMP3 1,294.7 2,646.0 hMMP7 14.7 43.7 hMMP8 95.9 249.4 hMMP9 10,034.6 29,201.5 hNGAL 1,968.1 2,608.9 hPDGFAA 18.6 21.8 hPDGFAB 6.2 55.5 hPDGFBB 15.1 5.2 hPEDF 9,216.2 576,962.0 hSDF1b 85.9 15.3 hTGFa 0.0 0.0 hTGFb1 377.5 410.9 hTGFb2 11.2 20.7 hTIMP1 12,279.0 15,562.7 hTIMP2 216.7 419.6 hTSP1 223.1 0.0 hTSP2 42.7 210.7 hVEGF 53.1 45.9 hVEGFC 197.4 182.7

Example 17 Interferon 2α (IFN-2α) and Transforming Growth Factor-β3 (TGF-β3)

Placental products described in this invention have been analyzed for the presence of IFN-2α and TGF-β3. Briefly, after thawing, the membranes were homogenized and centrifuged at 16,000 g to collect the resulting supernatants. Supernatants were analyzed on a commercially available ELISA kit from MabTech (IFN-2α) and R&D Systems (TGF-β3).

FIG. 12 shows significant expression of IFN-2α (A) and TGF-β3 (B) in cellular chorionic membrane homogenates.

Without being bound by theory, interferon-2α and TGF-β3 may aid in the prevention of scar and contracture formation. IFN-2α may serve a role to decrease collagen and fibronectin synthesis and fibroblast-mediated wound contracture.

Example 18 Tissue Reparative Proteins in Chorionic Membranes

Chorionic membrane homogenates were analyzed for the presence of proteins that are important in tissue repair.

Chorionic membranes described in this invention have been analyzed for the presence of tissue reparative proteins. Briefly, amniotic membranes were incubated in DMEM+10% FBS for 72 hrs. The membranes were then homogenized in a bead homogenizer with the culture media. The homogenates were centrifuged, and the supernatants were analyzed on commercially available ELISA kits from R&D Systems. Error! Not a valid bookmark self-reference. shows significant expression of BMP-2, BMP-4, PLAB, PIGF, and IGF-1 in several donors of chorionic membranes.

Without being bound by theory, the inventors believe that efficacy of the present placental products for wound repair are due, in part, to the role of BMPs, IGF-1, and PIGF in the development and homeostasis of various tissues by regulating key cellular processes. BMP-2 and BMP-4 may stimulate differentiation of MSCs to osteoblasts in addition to promote cell growth; placental BMP or PLAB is a novel member of the BMP family that is suggested to mediate embryonic development. Insulin-like growth factor 1 (IGF-1) may promotes proliferation and differentiation of osteoprogenitor cells. Placental derived growth factor (PIGF) may acts as a mitogen for osteoblasts.

Example 19 MMPs and TIMPs

Both MMPs and TIMPs are among the factors that are important for wound healing. However, expression of these proteins must be highly regulated and coordinated. Excess of MMPs versus TIMPS is a marker of poor chronic wound healing. We investigated expression of MMPs and TIMPs and its ratio in amniotic membrane and chorionic membrane and compared it to the expression profile in Apligraf and Dermagraft.

Results showed that all membranes express MMPs and TIMPs; the ratio in the thawed placental products and amniotic membranes is significantly lower. Therefore, the placental products (optionally including chorionic membranes) will be more beneficial for wound healing.

Accumulated data indicate that the MMP to TIMP ratio is higher in cases of non-healing wounds. For example, the ratio between MMP-9 and TIMP1 is approximately 7-10 to one or good healing and 18-20 to one or higher for poor healing.

As shown in FIG. 14, analysis of the ratio between MMPs and TIMPs secreted by placental tissues, Apligraf, and Dermagraft showed that the chorionic membrane products contain MMPs and TIMPs at an approximate ratio of 7, which is favorable for wound healing. In contrast, Dermagraft had a ratio>20, and Apligraf had a ratio>200.

These data indicate that the present methods can produce placental products that comprise a chorionic membrane containing MMP-9 and TIMP1 at a ratio of about 7-10 to one.

Example 20 α2-Macroglobulin

α2-macroglobulin is known as a plasma protein that inactivates proteinases from all 4 mechanistic classes. Another important function of this protein is to serve as a reservoir for cytokines and growth factors, examples of which include TGF, PDGF, and FGF. In the chronic wounds like diabetic ulcers or venous ulcers, the presence of high amount of proteases leads to rapid degradation of growth factors and delays in wound healing. Thus, the presence of α2-macroglobulin in products designed for chronic wound healing will be beneficial. Results of the protein array analysis showed that amniotic and chorionic membranes contain α2-macroglobulin (Table 13).

These data indicate that the present methods can produce placental products that comprise a chorionic membrane containing α2-macroglobulin.

TABLE 13 Expression of α2-macroglobulin in placental tissue protein extracts. α2-macroglobulin Sample (pg/mL/cm²) AM75 7 CM75 790 AM78 53042 CM78 1014

Example 21 Establishment of bFGF as a Marker for Chorionic Tissue Potency

bFGF modulates a variety of cellular processes including angiogenesis, tissue repair, and wound healing (Presta et al., 2005, Reuss et al., 2003, and Su et al., 2008). In wound healing models, bFGF has been shown to increase wound closure and enhance vessel formation at the site of the wound (Greenhalgh et al., 1990). Evaluation of proteins derived from chorionic membranes prepared pursuant to the presently disclosed manufacturing process revealed that bFGF is one of the major factors in placental tissue protein extracts (FIG. 15). FIG. 15 depicts expression of bFGF by amniotic membranes (AM) and chorionic membranes (CM) detected during the protein profile evaluation of placental membranes.

The importance of bFGF for wound healing supports selection of bFGF as a potency marker for evaluation of chorionic membrane products manufactured for clinical use pursuant to the present disclosure. A commercially available ELISA kit from R&D Systems was selected for evaluation of its suitability to measure bFGF secreted by placental membranes. ELISA method qualification experiments were designed according to FDA and ICH guidances for bioanalytical assay validation (Validation of Analytical Procedures: Text and Methodology Q2 (R1), 1994; ICH Harmonized Tripartite Guideline and Guidance for Industry Bioanalytical Method Validation, 2001).

The ELISA procedure was performed according to the manufacturer's instructions (bFGF ELISA brochure). The evaluation of the kit was performed prior to measurement of bFGF in placental tissue samples. Assay performance was assessed by analyzing linearity, range, lower and upper limits of quantitation (LLOQ and ULOQ), precision, and accuracy. Experimental data suggested that the quantitation range of this assay was 40-1280 pg/mL bFGF. The intra- and inter-assay CVs ranged from 2.42 to 6.23% and 0.59 to 7.02%, respectively. Additionally, sample recovery analysis demonstrated accuracy within 20%. This assay showed dilutional linearity and specificity. Ruggedness was demonstrated by assay insensitivity to variations introduced by different analysts. The analytical performance of the bFGF ELISA indicated that this assay was suitable for the measurement of bFGF secreted by placental membranes. bFGF ELISA parameters are summarized in Table 14.

TABLE 14 Established ELISA parameters for measuring bFGF in placenta homogenates. Calibration Standard 20-1280 pg/mL Range Assay Quantitation 40-1280 pg/mL Range LLOQ 40 pg/mL LOD 20 pg/mL ULOQ 1280 pg/mL

bFGF Expression in Chorionic Membranes

Measurement of bFGF in chorionic membrane preparations has proven to be both reliable and reproducible. The placental tissue homogenates were prepared using the “bead” method as described above. Also, secretion of bFGF in tissue culture media was evaluated. Measurement of bFGF in multiple donors showed that this method of quantification was a valuable means of evaluating potency the presently disclosed tissue products prepared for use in a clinical setting. FIG. 16 shows representative expression of bFGF in chorionic tissue samples derived from two separate placenta donors. Results have been reproduced in multiple tissue preparations.

These data indicate that the present methods can produce placental products that comprise a chorionic membrane containing bFGF.

Example 22 Placental Tissues Enhance Cell Migration and Wound Healing

The process of wound healing is highly complex and involves a series of structured events controlled by growth factors (Goldman, 2004). These events include increased vascularization, infiltration by inflammatory immune cells, and increases in cell proliferation. The beginning stages of wound healing revolve around the ability of individual cells to polarize towards the wound and migrate into the wounded area in order to close the wound area and rebuild the surrounding tissue. Upon proper stimulation, several different types of cells including epithelial, endothelial, mesenchymal, and fibroblastic cells are implicated in the wound healing process (Pastar et al, 2008 and Bannasch et al., 2000). Specifically, they proliferate and migrate into the wound area to promote healing. Therefore, experiments were conducted to determine if factors secreted from amniotic and chorionic membranes produced pursuant to the present disclosure promote vrII migration and wound field closure. To accomplish this, a commercially available wound healing assay (Cell Biolabs) and a highly accepted human microvascular endothelial cell line (HMVEC, Lonza Inc.) were utilized. Results indicated that cell migration was enhanced by treatment with conditioned media from the placental membranes.

In Vitro Cell Migration

Human microvascular endothelial cells (HMVECs) were grown under normal cell culture conditions in defined complete media (Lonza Inc.). To assess migration and wound field closure, a commercially available wound healing assay was used (Cell Biolab). The assay principle is outlined in FIG. 17.

FIG. 17 depicts the Cell Biolabs 24-well Cytoselect wound healing assay. (Figure reproduced from Cell Biolabs).

Cells were collected via trypsinization, pelleted, and counted before being resuspended in complete media at a density of 2×10⁵ cells/mL. 250 μL (5×10⁴ cells) of cell suspension was then pipetted into each side of a well containing a wound healing insert (Cytoselect 24-well Wound Healing Assay Plate, Cell Biolabs). The cells were grown for 24 hours in complete media. After 24 hours, the wound inserts were removed. At the same time, complete media was removed and replaced with experimental media. Complete media and basal media were used as positive and negative controls, respectively. To generate experimental media, placental membranes were incubated for 3 days in DMEM with 1% human serum albumin (HSA) in a tissue culture incubator. The resulting tissue and media were then placed in eppendorf tubes and spun at high speed in a microcentrifuge. The supernatants were collected and stored at −80° C.±5° C. until use. For migration and wound healing studies, conditioned media from placental membranes was diluted 1:20 in basal media before being added to experimental wells. After 18 hours, the media was removed, and the cells were fixed for 20 min in 4% paraformaldehyde and stained with crystal violet. The wound field in each well was then photographed. Wound healing was determined by the amount of wound field still visible at the end of the experiment when compared to control pictures taken before conditioned media was added to the wells.

Placental Membrane Conditioned Media Supports Cell Migration and Wound Field Closure

Conditioned media from amniotic and chorionic membranes was used to assess the potential for these membranes to promote cell migration and wound field closure. Conditioned media from placental chorionic membranes supported migration of cells into the experimental wound field. FIG. 18 depicts representative images of HMVECs treated with 5% conditioned media from amniotic, chorionic, or a combination of amniotic/chorionic tissue as well as positive and negative controls. Wound field is 0.9 mm in width.

The ability of factors from placental membranes produced pursuant to the present disclosure to promote HMVEC migration indicated that these tissues have the ability to enhance wound healing. Additionally, based on the insight of the inventors, it has been surprisingly discovered that these tissues also enhance revascularization since the HMVEC cell line is derived from vascular endothelial cells.

These data demonstrate that the methods of manufacture according to the present invention produce placental products with unexpectedly superior levels of factors that promote wound healing.

Example 23 Analysis of Factors in Exemplary Placental Tissue Products

Table 15 depicts the biochemical profile of exemplary placental products of the invention (results adjusted per cm² after subtraction of the negative background).

TABLE 15 Factors in placental tissue product (pg/cm²) Units Apligraf Dermagraft AM75 CM75 AM78 CM78 hMMP1 pg/ml/cm² 1964945.37 14818.20 2821.85 3531.81 117326.89 95.46 hMMP7 pg/ml/cm² 911.54 0.00 0.00 0.00 3.96 0.00 hMMP10 pg/ml/cm² 0.00 0.00 113.94 0.00 0.00 0.00 hMMP13 pg/ml/cm² 21.61 0.00 0.00 0.00 0.71 0.00 hMMP3 pg/ml/cm² 208281.70 180721.52 170.26 161.52 8325.17 0.00 hMMP9 pg/ml/cm² 8872.28 19321.39 214.78 1455.11 630.56 57.59 hMMP2 pg/ml/cm² 153341.77 19712.21 287.14 37.93 3823.38 24.44 hMMP8 pg/ml/cm² 36.92 12.19 0.00 0.00 0.00 0.00 hTIMP1 pg/ml/cm² 2487.18 10909.84 569.23 883.05 28743.48 97.94 hTIMP2 pg/ml/cm² 7285.53 1796.56 89.29 13.72 424.06 4.83 MMP/TIMP 239.26 19.72 6.81 6.26 4.50 2.62

Example 24 Factors in Examplary Placental Products as Measured Through Protein Array Analysis by Aushon Biosystems

Table 16 depicts the biochemical profile of the lysates of examplary placental products of the invention (results adjusted per cm² after subtraction of the negative background).

TABLE 16 AM75 lysate AM78 lysate CM75 lysate CM78 lysate pg/ml pg/ml pg/ml pg/ml hACRP30 50.8 1154.6 1213.7 225.3 hAlpha2- 1910.6 426191.6 8174.4 9968.6 Macroglobulin hEGF 127.3 361.4 0.0 0.8 hbFGF 119.1 821.5 375.0 351.3 hGCSF 0.7 3.2 1.2 0.7 hHBEGF 127.5 168.0 15.4 84.5 hHGF 3943.7 15060.0 29979.6 50392.8 hIGFBP1 5065.0 9456.6 934.0 1443.6 hIGFBP2 12460.8 5569.7 135.9 134.6 hIGFBP3 50115.7 41551.4 4571.5 11970.2 hIL1ra 3881.0 32296.9 5168.2 525.5 hKGF 1.4 8.8 3.1 1.5 hLIF 0.0 4.2 0.0 0.0 hMMP1 9144.1 20641.2 2882.9 6582.3 hMMP10 0.0 15.5 79.3 87.5 hMMP2 2067.3 4061.9 949.5 748.8 hMMP3 0.0 36.2 0.0 0.0 hMMP7 5.1 11.4 4.5 9.1 hMMP8 0.0 0.0 0.0 0.0 hMMP9 92.2 2878.1 2676.2 1259.3 hNGAL 6900.1 6175.9 938.5 229.7 hPDGFAA 0.0 12.5 39.8 35.2 hPDGFAB 11.2 31.3 14.4 14.0 hPDGFbb 4.6 13.4 4.0 1.3 hPEDF 0.0 652.6 0.0 0.0 hTIMP1 7958.1 35955.6 50712.3 17419.9 hTIMP2 3821.8 7443.2 640.7 780.0 hVEGF 3.3 11.8 125.2 8.4 hVEGFC 46.5 150.0 123.5 51.7 hVEGFD 25.7 31.0 15.0 20.4 

1-33. (canceled)
 34. A method of manufacturing a placental product comprising the steps of: a. obtaining a placenta; b. selectively depleting the chorionic membrane of a substantial portion of one or more types of immunogenic cells, wherein i. the one or more types of immunogenic cells comprise trophoblasts, functional CD14+ macrophages, or both trophoblasts and functional CD14+ macrophage; and ii. the step of selective depletion does not comprise killing or removing substantially all native therapeutic cells; and c. cryopreserving the chorionic membrane in a cryopreservation medium.
 35. The method of claim 34, wherein the selective depletion step further comprises removing substantially all vascularized tissue or vascularized tissue-derived immunogenic cells from the placenta, or the chorionic membrane.
 36. The method of claim 34, wherein the selective depletion step comprises treating the placenta with a protease and removing a layer comprising the trophoblasts, and optionally, wherein the protease is dispase.
 37. The method of claim 34, wherein the selective depletion step comprises any of scraping the trophoblasts from the chorionic membrane, blunt dissection of the trophoblast layer from the chorionic membrane, and removal of the trophoblast layer without removing the basement membrane from the chorionic membrane.
 38. The method of claim 34, wherein the selective depletion of the functional CD14+ macrophages comprises selectively killing or inactivating the functional CD14+ macrophages.
 39. The method of claim 38, wherein the selective depletion of the functional CD14+ macrophages comprises refrigerating the placenta in the cryopreservation medium for a period of time before the step of cryopreservation.
 40. The method of claim 34, wherein the cryopreservation medium comprises a cell-permeating cryopreservative, a non-cell-permeating cryopreservative, or a combination thereof.
 41. The method of claim 39, wherein the cryopreservation medium comprises a cell-permeating cryopreservative comprising DMSO in amount of about 2% to about 20%.
 42. The method of claim 40, wherein the period of time is about 10 min to about 120 min.
 43. The method of claim 41, wherein the refrigerating comprises incubating the placenta for the period of time at a temperature of about 2° to about 8° C.
 44. The method of claim 43, wherein the step of cryopreserving comprises reducing the temperature at a rate of less than about 5° C./min.
 45. The method claim 34, wherein the selective depletion of functional CD14+ macrophages comprises treating the placenta with at least one of an anti-TNF-α antibody or IL-10.
 46. The method of claim 34, comprising the step of removing substantially all vascularized tissue or vascularized tissue-derived immunogenic cells from the placenta or the chorionic membrane by lysing red blood cells, removing blood clots from the placenta or a combination thereof.
 47. The method of claim 46, wherein said removing substantially all vascularized tissue or vascularized tissue-derived immunogenic cells comprises treating the placenta with an anticoagulant.
 48. The method of claim 34, further comprising the step of removing the amniotic membrane from the placenta.
 49. The method of claim 48, wherein at least about 15.9% of the amniotic epithelial cells are retained in the placental product.
 50. The method of claim 34, wherein the selective depletion step further comprises: a. removing substantially all vascularized tissue or vascularized tissue-derived immunogenic cells from the placenta, or the chorionic membrane; b. treating the placenta with a protease; c. removing a layer comprising the trophoblasts by any of scraping the trophoblasts from the chorionic membrane, blunt dissection of the trophoblast layer from the chorionic membrane, and removal of the trophoblast layer without removing the basement membrane from the chorionic membrane; and d. selectively killing or inactivating the functional CD14+ macrophages.
 51. A method of treating a tissue injury comprising administering a placental product of produced by the method of claim 34 to the tissue injury of a subject. 